Replace IOError with OSError (#16715)

121 files changed, 381 insertions, 386 deletions

diff --git a/Lib/_osx_support.py b/Lib/_osx_support.py
index 10767784bf..8412e45b70 100644
--- a/Lib/_osx_support.py
+++ b/Lib/_osx_support.py
@@ -94,7 +94,7 @@ def _get_system_version():
         _SYSTEM_VERSION = ''
         try:
             f = open('/System/Library/CoreServices/SystemVersion.plist')
-        except IOError:
+        except OSError:
             # We're on a plain darwin box, fall back to the default
             # behaviour.
             pass
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 583eb7f262..5ff9c0f018 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -34,7 +34,7 @@ BlockingIOError = BlockingIOError
 def open(file, mode="r", buffering=-1, encoding=None, errors=None,
          newline=None, closefd=True, opener=None):
 
-    r"""Open file and return a stream.  Raise IOError upon failure.
+    r"""Open file and return a stream.  Raise OSError upon failure.
 
     file is either a text or byte string giving the name (and the path
     if the file isn't in the current working directory) of the file to
@@ -254,7 +254,7 @@ class OpenWrapper:
 try:
     UnsupportedOperation = io.UnsupportedOperation
 except AttributeError:
-    class UnsupportedOperation(ValueError, IOError):
+    class UnsupportedOperation(ValueError, OSError):
         pass
 
 
@@ -278,7 +278,7 @@ class IOBase(metaclass=abc.ABCMeta):
     readinto) needed. Text I/O classes work with str data.
 
     Note that calling any method (even inquiries) on a closed stream is
-    undefined. Implementations may raise IOError in this case.
+    undefined. Implementations may raise OSError in this case.
 
     IOBase (and its subclasses) support the iterator protocol, meaning
     that an IOBase object can be iterated over yielding the lines in a
@@ -294,7 +294,7 @@ class IOBase(metaclass=abc.ABCMeta):
     ### Internal ###
 
     def _unsupported(self, name):
-        """Internal: raise an IOError exception for unsupported operations."""
+        """Internal: raise an OSError exception for unsupported operations."""
         raise UnsupportedOperation("%s.%s() not supported" %
                                    (self.__class__.__name__, name))
 
@@ -441,7 +441,7 @@ class IOBase(metaclass=abc.ABCMeta):
     def fileno(self):
         """Returns underlying file descriptor (an int) if one exists.
 
-        An IOError is raised if the IO object does not use a file descriptor.
+        An OSError is raised if the IO object does not use a file descriptor.
         """
         self._unsupported("fileno")
 
@@ -699,13 +699,13 @@ class _BufferedIOMixin(BufferedIOBase):
     def seek(self, pos, whence=0):
         new_position = self.raw.seek(pos, whence)
         if new_position < 0:
-            raise IOError("seek() returned an invalid position")
+            raise OSError("seek() returned an invalid position")
         return new_position
 
     def tell(self):
         pos = self.raw.tell()
         if pos < 0:
-            raise IOError("tell() returned an invalid position")
+            raise OSError("tell() returned an invalid position")
         return pos
 
     def truncate(self, pos=None):
@@ -927,7 +927,7 @@ class BufferedReader(_BufferedIOMixin):
         """Create a new buffered reader using the given readable raw IO object.
         """
         if not raw.readable():
-            raise IOError('"raw" argument must be readable.')
+            raise OSError('"raw" argument must be readable.')
 
         _BufferedIOMixin.__init__(self, raw)
         if buffer_size <= 0:
@@ -1074,7 +1074,7 @@ class BufferedWriter(_BufferedIOMixin):
 
     def __init__(self, raw, buffer_size=DEFAULT_BUFFER_SIZE):
         if not raw.writable():
-            raise IOError('"raw" argument must be writable.')
+            raise OSError('"raw" argument must be writable.')
 
         _BufferedIOMixin.__init__(self, raw)
         if buffer_size <= 0:
@@ -1138,7 +1138,7 @@ class BufferedWriter(_BufferedIOMixin):
                     errno.EAGAIN,
                     "write could not complete without blocking", 0)
             if n > len(self._write_buf) or n < 0:
-                raise IOError("write() returned incorrect number of bytes")
+                raise OSError("write() returned incorrect number of bytes")
             del self._write_buf[:n]
 
     def tell(self):
@@ -1174,10 +1174,10 @@ class BufferedRWPair(BufferedIOBase):
         The arguments are two RawIO instances.
         """
         if not reader.readable():
-            raise IOError('"reader" argument must be readable.')
+            raise OSError('"reader" argument must be readable.')
 
         if not writer.writable():
-            raise IOError('"writer" argument must be writable.')
+            raise OSError('"writer" argument must be writable.')
 
         self.reader = BufferedReader(reader, buffer_size)
         self.writer = BufferedWriter(writer, buffer_size)
@@ -1248,7 +1248,7 @@ class BufferedRandom(BufferedWriter, BufferedReader):
         with self._read_lock:
             self._reset_read_buf()
         if pos < 0:
-            raise IOError("seek() returned invalid position")
+            raise OSError("seek() returned invalid position")
         return pos
 
     def tell(self):
@@ -1727,7 +1727,7 @@ class TextIOWrapper(TextIOBase):
         if not self._seekable:
             raise UnsupportedOperation("underlying stream is not seekable")
         if not self._telling:
-            raise IOError("telling position disabled by next() call")
+            raise OSError("telling position disabled by next() call")
         self.flush()
         position = self.buffer.tell()
         decoder = self._decoder
@@ -1814,7 +1814,7 @@ class TextIOWrapper(TextIOBase):
                 chars_decoded += len(decoder.decode(b'', final=True))
                 need_eof = 1
                 if chars_decoded < chars_to_skip:
-                    raise IOError("can't reconstruct logical file position")
+                    raise OSError("can't reconstruct logical file position")
 
             # The returned cookie corresponds to the last safe start point.
             return self._pack_cookie(
@@ -1891,7 +1891,7 @@ class TextIOWrapper(TextIOBase):
 
             # Skip chars_to_skip of the decoded characters.
             if len(self._decoded_chars) < chars_to_skip:
-                raise IOError("can't restore logical file position")
+                raise OSError("can't restore logical file position")
             self._decoded_chars_used = chars_to_skip
 
         # Finally, reset the encoder (merely useful for proper BOM handling)
diff --git a/Lib/argparse.py b/Lib/argparse.py
index 3b1a079552..1c07110816 100644
--- a/Lib/argparse.py
+++ b/Lib/argparse.py
@@ -1167,7 +1167,7 @@ class FileType(object):
         try:
             return open(string, self._mode, self._bufsize, self._encoding,
                         self._errors)
-        except IOError as e:
+        except OSError as e:
             message = _("can't open '%s': %s")
             raise ArgumentTypeError(message % (string, e))
 
@@ -2020,7 +2020,7 @@ class ArgumentParser(_AttributeHolder, _ActionsContainer):
                         new_arg_strings.extend(arg_strings)
                     finally:
                         args_file.close()
-                except IOError:
+                except OSError:
                     err = _sys.exc_info()[1]
                     self.error(str(err))
 
diff --git a/Lib/cgi.py b/Lib/cgi.py
index 8cc48bd78b..dda848424a 100755
--- a/Lib/cgi.py
+++ b/Lib/cgi.py
@@ -80,7 +80,7 @@ def initlog(*allargs):
     if logfile and not logfp:
         try:
             logfp = open(logfile, "a")
-        except IOError:
+        except OSError:
             pass
     if not logfp:
         log = nolog
diff --git a/Lib/chunk.py b/Lib/chunk.py
index 5863ed0846..dc90a7522e 100644
--- a/Lib/chunk.py
+++ b/Lib/chunk.py
@@ -70,7 +70,7 @@ class Chunk:
         self.size_read = 0
         try:
             self.offset = self.file.tell()
-        except (AttributeError, IOError):
+        except (AttributeError, OSError):
             self.seekable = False
         else:
             self.seekable = True
@@ -102,7 +102,7 @@ class Chunk:
         if self.closed:
             raise ValueError("I/O operation on closed file")
         if not self.seekable:
-            raise IOError("cannot seek")
+            raise OSError("cannot seek")
         if whence == 1:
             pos = pos + self.size_read
         elif whence == 2:
@@ -158,7 +158,7 @@ class Chunk:
                 self.file.seek(n, 1)
                 self.size_read = self.size_read + n
                 return
-            except IOError:
+            except OSError:
                 pass
         while self.size_read < self.chunksize:
             n = min(8192, self.chunksize - self.size_read)
diff --git a/Lib/compileall.py b/Lib/compileall.py
index a47e84fd60..a8e9a31291 100644
--- a/Lib/compileall.py
+++ b/Lib/compileall.py
@@ -106,7 +106,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=False,
                         actual = chandle.read(8)
                     if expect == actual:
                         return success
-                except IOError:
+                except OSError:
                     pass
             if not quiet:
                 print('Compiling {!r}...'.format(fullname))
@@ -124,7 +124,7 @@ def compile_file(fullname, ddir=None, force=False, rx=None, quiet=False,
                 msg = msg.decode(sys.stdout.encoding)
                 print(msg)
                 success = 0
-            except (SyntaxError, UnicodeError, IOError) as e:
+            except (SyntaxError, UnicodeError, OSError) as e:
                 if quiet:
                     print('*** Error compiling {!r}...'.format(fullname))
                 else:
diff --git a/Lib/configparser.py b/Lib/configparser.py
index 9d5f779a12..ea8465286c 100644
--- a/Lib/configparser.py
+++ b/Lib/configparser.py
@@ -688,7 +688,7 @@ class RawConfigParser(MutableMapping):
             try:
                 with open(filename, encoding=encoding) as fp:
                     self._read(fp, filename)
-            except IOError:
+            except OSError:
                 continue
             read_ok.append(filename)
         return read_ok
diff --git a/Lib/dbm/__init__.py b/Lib/dbm/__init__.py
index 3bff1700b5..0609e4990c 100644
--- a/Lib/dbm/__init__.py
+++ b/Lib/dbm/__init__.py
@@ -42,7 +42,7 @@ _names = ['dbm.gnu', 'dbm.ndbm', 'dbm.dumb']
 _defaultmod = None
 _modules = {}
 
-error = (error, IOError)
+error = (error, OSError)
 
 
 def open(file, flag='r', mode=0o666):
@@ -109,7 +109,7 @@ def whichdb(filename):
         f = io.open(filename + ".dir", "rb")
         f.close()
         return "dbm.ndbm"
-    except IOError:
+    except OSError:
         # some dbm emulations based on Berkeley DB generate a .db file
         # some do not, but they should be caught by the bsd checks
         try:
@@ -122,7 +122,7 @@ def whichdb(filename):
                 d = ndbm.open(filename)
                 d.close()
                 return "dbm.ndbm"
-        except IOError:
+        except OSError:
             pass
 
     # Check for dumbdbm next -- this has a .dir and a .dat file
@@ -139,13 +139,13 @@ def whichdb(filename):
                 return "dbm.dumb"
         finally:
             f.close()
-    except (OSError, IOError):
+    except OSError:
         pass
 
     # See if the file exists, return None if not
     try:
         f = io.open(filename, "rb")
-    except IOError:
+    except OSError:
         return None
 
     # Read the start of the file -- the magic number
diff --git a/Lib/dbm/dumb.py b/Lib/dbm/dumb.py
index 0bb3a898e4..9ac7852978 100644
--- a/Lib/dbm/dumb.py
+++ b/Lib/dbm/dumb.py
@@ -29,7 +29,7 @@ __all__ = ["error", "open"]
 
 _BLOCKSIZE = 512
 
-error = IOError
+error = OSError
 
 class _Database(collections.MutableMapping):
 
@@ -67,7 +67,7 @@ class _Database(collections.MutableMapping):
         # Mod by Jack: create data file if needed
         try:
             f = _io.open(self._datfile, 'r', encoding="Latin-1")
-        except IOError:
+        except OSError:
             f = _io.open(self._datfile, 'w', encoding="Latin-1")
             self._chmod(self._datfile)
         f.close()
@@ -78,7 +78,7 @@ class _Database(collections.MutableMapping):
         self._index = {}
         try:
             f = _io.open(self._dirfile, 'r', encoding="Latin-1")
-        except IOError:
+        except OSError:
             pass
         else:
             for line in f:
diff --git a/Lib/distutils/command/build_scripts.py b/Lib/distutils/command/build_scripts.py
index 4b5b22ec20..90a8380a04 100644
--- a/Lib/distutils/command/build_scripts.py
+++ b/Lib/distutils/command/build_scripts.py
@@ -74,7 +74,7 @@ class build_scripts(Command):
             # script.
             try:
                 f = open(script, "rb")
-            except IOError:
+            except OSError:
                 if not self.dry_run:
                     raise
                 f = None
diff --git a/Lib/distutils/core.py b/Lib/distutils/core.py
index a43d72588b..91e5132934 100644
--- a/Lib/distutils/core.py
+++ b/Lib/distutils/core.py
@@ -148,7 +148,7 @@ def setup (**attrs):
             dist.run_commands()
         except KeyboardInterrupt:
             raise SystemExit("interrupted")
-        except (IOError, OSError) as exc:
+        except OSError as exc:
             error = grok_environment_error(exc)
 
             if DEBUG:
diff --git a/Lib/distutils/cygwinccompiler.py b/Lib/distutils/cygwinccompiler.py
index 0bdd539c37..0c23ab1b7f 100644
--- a/Lib/distutils/cygwinccompiler.py
+++ b/Lib/distutils/cygwinccompiler.py
@@ -359,7 +359,7 @@ def check_config_h():
                 return CONFIG_H_NOTOK, "'%s' does not mention '__GNUC__'" % fn
         finally:
             config_h.close()
-    except IOError as exc:
+    except OSError as exc:
         return (CONFIG_H_UNCERTAIN,
                 "couldn't read '%s': %s" % (fn, exc.strerror))
 
diff --git a/Lib/distutils/dir_util.py b/Lib/distutils/dir_util.py
index 7d1c78ab29..2b35aa318e 100644
--- a/Lib/distutils/dir_util.py
+++ b/Lib/distutils/dir_util.py
@@ -198,7 +198,7 @@ def remove_tree(directory, verbose=1, dry_run=0):
             abspath = os.path.abspath(cmd[1])
             if abspath in _path_created:
                 del _path_created[abspath]
-        except (IOError, OSError) as exc:
+        except OSError as exc:
             log.warn(grok_environment_error(
                     exc, "error removing %s: " % directory))
 
diff --git a/Lib/distutils/errors.py b/Lib/distutils/errors.py
index eb13c983e9..8b93059e19 100644
--- a/Lib/distutils/errors.py
+++ b/Lib/distutils/errors.py
@@ -35,8 +35,8 @@ class DistutilsArgError (DistutilsError):
 
 class DistutilsFileError (DistutilsError):
     """Any problems in the filesystem: expected file not found, etc.
-    Typically this is for problems that we detect before IOError or
-    OSError could be raised."""
+    Typically this is for problems that we detect before OSError
+    could be raised."""
     pass
 
 class DistutilsOptionError (DistutilsError):
diff --git a/Lib/distutils/msvc9compiler.py b/Lib/distutils/msvc9compiler.py
index b3f6ce10a8..9688f20019 100644
--- a/Lib/distutils/msvc9compiler.py
+++ b/Lib/distutils/msvc9compiler.py
@@ -729,7 +729,7 @@ class MSVCCompiler(CCompiler) :
                 return manifest_file
             finally:
                 manifest_f.close()
-        except IOError:
+        except OSError:
             pass
 
     # -- Miscellaneous methods -----------------------------------------
diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index 3b6549fccc..91ed1a498c 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -426,7 +426,7 @@ def _init_posix():
     try:
         filename = get_makefile_filename()
         parse_makefile(filename, g)
-    except IOError as msg:
+    except OSError as msg:
         my_msg = "invalid Python installation: unable to open %s" % filename
         if hasattr(msg, "strerror"):
             my_msg = my_msg + " (%s)" % msg.strerror
@@ -438,7 +438,7 @@ def _init_posix():
         filename = get_config_h_filename()
         with open(filename) as file:
             parse_config_h(file, g)
-    except IOError as msg:
+    except OSError as msg:
         my_msg = "invalid Python installation: unable to open %s" % filename
         if hasattr(msg, "strerror"):
             my_msg = my_msg + " (%s)" % msg.strerror
diff --git a/Lib/distutils/util.py b/Lib/distutils/util.py
index ba09ac450a..a2f9544519 100644
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -207,8 +207,8 @@ def subst_vars (s, local_vars):
 
 
 def grok_environment_error (exc, prefix="error: "):
-    """Generate a useful error message from an EnvironmentError (IOError or
-    OSError) exception object.  Handles Python 1.5.1 and 1.5.2 styles, and
+    """Generate a useful error message from an OSError
+    exception object.  Handles Python 1.5.1 and 1.5.2 styles, and
     does what it can to deal with exception objects that don't have a
     filename (which happens when the error is due to a two-file operation,
     such as 'rename()' or 'link()'.  Returns the error message as a string
diff --git a/Lib/fileinput.py b/Lib/fileinput.py
index 5be0318c41..f9bb88a621 100644
--- a/Lib/fileinput.py
+++ b/Lib/fileinput.py
@@ -30,7 +30,7 @@ pertaining to the last line read; nextfile() has no effect.
 
 All files are opened in text mode by default, you can override this by
 setting the mode parameter to input() or FileInput.__init__().
-If an I/O error occurs during opening or reading a file, the IOError
+If an I/O error occurs during opening or reading a file, the OSError
 exception is raised.
 
 If sys.stdin is used more than once, the second and further use will
@@ -328,7 +328,7 @@ class FileInput:
                         os.unlink(self._backupfilename)
                     except OSError:
                         pass
-                    # The next few lines may raise IOError
+                    # The next few lines may raise OSError
                     os.rename(self._filename, self._backupfilename)
                     self._file = open(self._backupfilename, self._mode)
                     try:
@@ -350,7 +350,7 @@ class FileInput:
                     self._savestdout = sys.stdout
                     sys.stdout = self._output
                 else:
-                    # This may raise IOError
+                    # This may raise OSError
                     if self._openhook:
                         self._file = self._openhook(self._filename, self._mode)
                     else:
diff --git a/Lib/ftplib.py b/Lib/ftplib.py
index 2641a1d5c4..6aecd28a13 100644
--- a/Lib/ftplib.py
+++ b/Lib/ftplib.py
@@ -61,7 +61,7 @@ class error_proto(Error): pass          # response does not begin with [1-5]
 
 # All exceptions (hopefully) that may be raised here and that aren't
 # (always) programming errors on our side
-all_errors = (Error, IOError, EOFError)
+all_errors = (Error, OSError, EOFError)
 
 
 # Line terminators (we always output CRLF, but accept any of CRLF, CR, LF)
@@ -826,7 +826,7 @@ else:
             return resp
 
     __all__.append('FTP_TLS')
-    all_errors = (Error, IOError, EOFError, ssl.SSLError)
+    all_errors = (Error, OSError, EOFError, ssl.SSLError)
 
 
 _150_re = None
@@ -958,7 +958,7 @@ class Netrc:
                 filename = os.path.join(os.environ["HOME"],
                                         ".netrc")
             else:
-                raise IOError("specify file to load or set $HOME")
+                raise OSError("specify file to load or set $HOME")
         self.__hosts = {}
         self.__macros = {}
         fp = open(filename, "r")
@@ -1074,7 +1074,7 @@ def test():
     userid = passwd = acct = ''
     try:
         netrc = Netrc(rcfile)
-    except IOError:
+    except OSError:
         if rcfile is not None:
             sys.stderr.write("Could not open account file"
                              " -- using anonymous login.")
diff --git a/Lib/gettext.py b/Lib/gettext.py
index e43f044cc7..05d9c1e5a3 100644
--- a/Lib/gettext.py
+++ b/Lib/gettext.py
@@ -244,7 +244,7 @@ class GNUTranslations(NullTranslations):
             version, msgcount, masteridx, transidx = unpack('>4I', buf[4:20])
             ii = '>II'
         else:
-            raise IOError(0, 'Bad magic number', filename)
+            raise OSError(0, 'Bad magic number', filename)
         # Now put all messages from the .mo file buffer into the catalog
         # dictionary.
         for i in range(0, msgcount):
@@ -256,7 +256,7 @@ class GNUTranslations(NullTranslations):
                 msg = buf[moff:mend]
                 tmsg = buf[toff:tend]
             else:
-                raise IOError(0, 'File is corrupt', filename)
+                raise OSError(0, 'File is corrupt', filename)
             # See if we're looking at GNU .mo conventions for metadata
             if mlen == 0:
                 # Catalog description
@@ -398,7 +398,7 @@ def translation(domain, localedir=None, languages=None,
     if not mofiles:
         if fallback:
             return NullTranslations()
-        raise IOError(ENOENT, 'No translation file found for domain', domain)
+        raise OSError(ENOENT, 'No translation file found for domain', domain)
     # Avoid opening, reading, and parsing the .mo file after it's been done
     # once.
     result = None
@@ -460,7 +460,7 @@ def dgettext(domain, message):
     try:
         t = translation(domain, _localedirs.get(domain, None),
                         codeset=_localecodesets.get(domain))
-    except IOError:
+    except OSError:
         return message
     return t.gettext(message)
 
@@ -468,7 +468,7 @@ def ldgettext(domain, message):
     try:
         t = translation(domain, _localedirs.get(domain, None),
                         codeset=_localecodesets.get(domain))
-    except IOError:
+    except OSError:
         return message
     return t.lgettext(message)
 
@@ -476,7 +476,7 @@ def dngettext(domain, msgid1, msgid2, n):
     try:
         t = translation(domain, _localedirs.get(domain, None),
                         codeset=_localecodesets.get(domain))
-    except IOError:
+    except OSError:
         if n == 1:
             return msgid1
         else:
@@ -487,7 +487,7 @@ def ldngettext(domain, msgid1, msgid2, n):
     try:
         t = translation(domain, _localedirs.get(domain, None),
                         codeset=_localecodesets.get(domain))
-    except IOError:
+    except OSError:
         if n == 1:
             return msgid1
         else:
diff --git a/Lib/gzip.py b/Lib/gzip.py
index 998a8e5d05..698f0c2747 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -287,10 +287,10 @@ class GzipFile(io.BufferedIOBase):
             raise EOFError("Reached EOF")
 
         if magic != b'\037\213':
-            raise IOError('Not a gzipped file')
+            raise OSError('Not a gzipped file')
         method = ord( self.fileobj.read(1) )
         if method != 8:
-            raise IOError('Unknown compression method')
+            raise OSError('Unknown compression method')
         flag = ord( self.fileobj.read(1) )
         self.mtime = read32(self.fileobj)
         # extraflag = self.fileobj.read(1)
@@ -326,7 +326,7 @@ class GzipFile(io.BufferedIOBase):
         self._check_closed()
         if self.mode != WRITE:
             import errno
-            raise IOError(errno.EBADF, "write() on read-only GzipFile object")
+            raise OSError(errno.EBADF, "write() on read-only GzipFile object")
 
         if self.fileobj is None:
             raise ValueError("write() on closed GzipFile object")
@@ -347,7 +347,7 @@ class GzipFile(io.BufferedIOBase):
         self._check_closed()
         if self.mode != READ:
             import errno
-            raise IOError(errno.EBADF, "read() on write-only GzipFile object")
+            raise OSError(errno.EBADF, "read() on write-only GzipFile object")
 
         if self.extrasize <= 0 and self.fileobj is None:
             return b''
@@ -380,7 +380,7 @@ class GzipFile(io.BufferedIOBase):
         self._check_closed()
         if self.mode != READ:
             import errno
-            raise IOError(errno.EBADF, "read1() on write-only GzipFile object")
+            raise OSError(errno.EBADF, "read1() on write-only GzipFile object")
 
         if self.extrasize <= 0 and self.fileobj is None:
             return b''
@@ -404,7 +404,7 @@ class GzipFile(io.BufferedIOBase):
     def peek(self, n):
         if self.mode != READ:
             import errno
-            raise IOError(errno.EBADF, "peek() on write-only GzipFile object")
+            raise OSError(errno.EBADF, "peek() on write-only GzipFile object")
 
         # Do not return ridiculously small buffers, for one common idiom
         # is to call peek(1) and expect more bytes in return.
@@ -487,10 +487,10 @@ class GzipFile(io.BufferedIOBase):
         crc32 = read32(self.fileobj)
         isize = read32(self.fileobj)  # may exceed 2GB
         if crc32 != self.crc:
-            raise IOError("CRC check failed %s != %s" % (hex(crc32),
+            raise OSError("CRC check failed %s != %s" % (hex(crc32),
                                                          hex(self.crc)))
         elif isize != (self.size & 0xffffffff):
-            raise IOError("Incorrect length of data produced")
+            raise OSError("Incorrect length of data produced")
 
         # Gzip files can be padded with zeroes and still have archives.
         # Consume all zero bytes and set the file position to the first
@@ -539,7 +539,7 @@ class GzipFile(io.BufferedIOBase):
         '''Return the uncompressed stream file position indicator to the
         beginning of the file'''
         if self.mode != READ:
-            raise IOError("Can't rewind in write mode")
+            raise OSError("Can't rewind in write mode")
         self.fileobj.seek(0)
         self._new_member = True
         self.extrabuf = b""
@@ -564,7 +564,7 @@ class GzipFile(io.BufferedIOBase):
                 raise ValueError('Seek from end not supported')
         if self.mode == WRITE:
             if offset < self.offset:
-                raise IOError('Negative seek in write mode')
+                raise OSError('Negative seek in write mode')
             count = offset - self.offset
             chunk = bytes(1024)
             for i in range(count // 1024):
diff --git a/Lib/http/cookiejar.py b/Lib/http/cookiejar.py
index a77dc3fc5d..7928e9b0e8 100644
--- a/Lib/http/cookiejar.py
+++ b/Lib/http/cookiejar.py
@@ -1730,8 +1730,8 @@ class CookieJar:
         return "<%s[%s]>" % (self.__class__, ", ".join(r))
 
 
-# derives from IOError for backwards-compatibility with Python 2.4.0
-class LoadError(IOError): pass
+# derives from OSError for backwards-compatibility with Python 2.4.0
+class LoadError(OSError): pass
 
 class FileCookieJar(CookieJar):
     """CookieJar that can be loaded from and saved to a file."""
@@ -1771,7 +1771,7 @@ class FileCookieJar(CookieJar):
                ignore_discard=False, ignore_expires=False):
         """Clear all cookies and reload cookies from a saved file.
 
-        Raises LoadError (or IOError) if reversion is not successful; the
+        Raises LoadError (or OSError) if reversion is not successful; the
         object's state will not be altered if this happens.
 
         """
@@ -1786,7 +1786,7 @@ class FileCookieJar(CookieJar):
             self._cookies = {}
             try:
                 self.load(filename, ignore_discard, ignore_expires)
-            except (LoadError, IOError):
+            except OSError:
                 self._cookies = old_state
                 raise
 
@@ -1937,8 +1937,7 @@ class LWPCookieJar(FileCookieJar):
                     if not ignore_expires and c.is_expired(now):
                         continue
                     self.set_cookie(c)
-
-        except IOError:
+        except OSError:
             raise
         except Exception:
             _warn_unhandled_exception()
@@ -2044,7 +2043,7 @@ class MozillaCookieJar(FileCookieJar):
                     continue
                 self.set_cookie(c)
 
-        except IOError:
+        except OSError:
             raise
         except Exception:
             _warn_unhandled_exception()
diff --git a/Lib/http/server.py b/Lib/http/server.py
index e54998237c..1873b13105 100644
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -711,7 +711,7 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         ctype = self.guess_type(path)
         try:
             f = open(path, 'rb')
-        except IOError:
+        except OSError:
             self.send_error(404, "File not found")
             return None
         self.send_response(200)
diff --git a/Lib/idlelib/EditorWindow.py b/Lib/idlelib/EditorWindow.py
index 2fe9447427..aed4d6acda 100644
--- a/Lib/idlelib/EditorWindow.py
+++ b/Lib/idlelib/EditorWindow.py
@@ -886,7 +886,7 @@ class EditorWindow(object):
             with open(self.recent_files_path, 'w',
                         encoding='utf_8', errors='replace') as rf_file:
                 rf_file.writelines(rf_list)
-        except IOError as err:
+        except OSError as err:
             if not getattr(self.root, "recentfilelist_error_displayed", False):
                 self.root.recentfilelist_error_displayed = True
                 tkMessageBox.showerror(title='IDLE Error',
diff --git a/Lib/idlelib/GrepDialog.py b/Lib/idlelib/GrepDialog.py
index 1450f7a24e..1d8d51b593 100644
--- a/Lib/idlelib/GrepDialog.py
+++ b/Lib/idlelib/GrepDialog.py
@@ -82,7 +82,7 @@ class GrepDialog(SearchDialogBase):
         for fn in list:
             try:
                 f = open(fn, errors='replace')
-            except IOError as msg:
+            except OSError as msg:
                 print(msg)
                 continue
             lineno = 0
diff --git a/Lib/idlelib/IOBinding.py b/Lib/idlelib/IOBinding.py
index 62c62b0a1b..9b63928860 100644
--- a/Lib/idlelib/IOBinding.py
+++ b/Lib/idlelib/IOBinding.py
@@ -212,7 +212,7 @@ class IOBinding:
             f.seek(0)
             bytes = f.read()
             f.close()
-        except IOError as msg:
+        except OSError as msg:
             tkMessageBox.showerror("I/O Error", str(msg), master=self.text)
             return False
         chars, converted = self._decode(two_lines, bytes)
@@ -377,7 +377,7 @@ class IOBinding:
             f.flush()
             f.close()
             return True
-        except IOError as msg:
+        except OSError as msg:
             tkMessageBox.showerror("I/O Error", str(msg),
                                    master=self.text)
             return False
diff --git a/Lib/idlelib/OutputWindow.py b/Lib/idlelib/OutputWindow.py
index 745ccd2613..9dacc492b5 100644
--- a/Lib/idlelib/OutputWindow.py
+++ b/Lib/idlelib/OutputWindow.py
@@ -106,7 +106,7 @@ class OutputWindow(EditorWindow):
                     f = open(filename, "r")
                     f.close()
                     break
-                except IOError:
+                except OSError:
                     continue
         else:
             return None
diff --git a/Lib/idlelib/PyShell.py b/Lib/idlelib/PyShell.py
index 696d363ade..6a9ed325db 100644
--- a/Lib/idlelib/PyShell.py
+++ b/Lib/idlelib/PyShell.py
@@ -58,7 +58,7 @@ else:
         try:
             file.write(warnings.formatwarning(message, category, filename,
                                               lineno, line=line))
-        except IOError:
+        except OSError:
             pass  ## file (probably __stderr__) is invalid, warning dropped.
     warnings.showwarning = idle_showwarning
     def idle_formatwarning(message, category, filename, lineno, line=None):
@@ -211,7 +211,7 @@ class PyShellEditorWindow(EditorWindow):
         try:
             with open(self.breakpointPath, "r") as fp:
                 lines = fp.readlines()
-        except IOError:
+        except OSError:
             lines = []
         try:
             with open(self.breakpointPath, "w") as new_file:
@@ -222,7 +222,7 @@ class PyShellEditorWindow(EditorWindow):
                 breaks = self.breakpoints
                 if breaks:
                     new_file.write(filename + '=' + str(breaks) + '\n')
-        except IOError as err:
+        except OSError as err:
             if not getattr(self.root, "breakpoint_error_displayed", False):
                 self.root.breakpoint_error_displayed = True
                 tkMessageBox.showerror(title='IDLE Error',
@@ -528,7 +528,7 @@ class ModifiedInterpreter(InteractiveInterpreter):
             return
         try:
             response = clt.pollresponse(self.active_seq, wait=0.05)
-        except (EOFError, IOError, KeyboardInterrupt):
+        except (EOFError, OSError, KeyboardInterrupt):
             # lost connection or subprocess terminated itself, restart
             # [the KBI is from rpc.SocketIO.handle_EOF()]
             if self.tkconsole.closing:
diff --git a/Lib/idlelib/configHandler.py b/Lib/idlelib/configHandler.py
index 405c7a138e..a193eb99f8 100644
--- a/Lib/idlelib/configHandler.py
+++ b/Lib/idlelib/configHandler.py
@@ -142,7 +142,7 @@ class IdleUserConfParser(IdleConfParser):
             fname = self.file
             try:
                 cfgFile = open(fname, 'w')
-            except IOError:
+            except OSError:
                 os.unlink(fname)
                 cfgFile = open(fname, 'w')
             with cfgFile:
@@ -207,7 +207,7 @@ class IdleConf:
                         userDir+',\n but the path does not exist.\n')
                 try:
                     sys.stderr.write(warn)
-                except IOError:
+                except OSError:
                     pass
                 userDir = '~'
         if userDir == "~": # still no path to home!
@@ -217,7 +217,7 @@ class IdleConf:
         if not os.path.exists(userDir):
             try:
                 os.mkdir(userDir)
-            except (OSError, IOError):
+            except OSError:
                 warn = ('\n Warning: unable to create user config directory\n'+
                         userDir+'\n Check path and permissions.\n Exiting!\n\n')
                 sys.stderr.write(warn)
@@ -251,7 +251,7 @@ class IdleConf:
                                                      raw=raw)))
             try:
                 sys.stderr.write(warning)
-            except IOError:
+            except OSError:
                 pass
         try:
             if self.defaultCfg[configType].has_option(section,option):
@@ -268,7 +268,7 @@ class IdleConf:
                        (option, section, default))
             try:
                 sys.stderr.write(warning)
-            except IOError:
+            except OSError:
                 pass
         return default
 
@@ -380,7 +380,7 @@ class IdleConf:
                            (element, themeName, theme[element]))
                 try:
                     sys.stderr.write(warning)
-                except IOError:
+                except OSError:
                     pass
             colour=cfgParser.Get(themeName,element,default=theme[element])
             theme[element]=colour
@@ -637,7 +637,7 @@ class IdleConf:
                                (event, keySetName, keyBindings[event]))
                     try:
                         sys.stderr.write(warning)
-                    except IOError:
+                    except OSError:
                         pass
         return keyBindings
 
diff --git a/Lib/idlelib/rpc.py b/Lib/idlelib/rpc.py
index 44b34308b7..2bf4fdf8cf 100644
--- a/Lib/idlelib/rpc.py
+++ b/Lib/idlelib/rpc.py
@@ -339,7 +339,7 @@ class SocketIO(object):
                 r, w, x = select.select([], [self.sock], [])
                 n = self.sock.send(s[:BUFSIZE])
             except (AttributeError, TypeError):
-                raise IOError("socket no longer exists")
+                raise OSError("socket no longer exists")
             except OSError:
                 raise
             else:
diff --git a/Lib/idlelib/textView.py b/Lib/idlelib/textView.py
index 1eaa4649ed..ae1f195a5b 100644
--- a/Lib/idlelib/textView.py
+++ b/Lib/idlelib/textView.py
@@ -66,7 +66,7 @@ def view_file(parent, title, filename, encoding=None, modal=True):
     try:
         with open(filename, 'r', encoding=encoding) as file:
             contents = file.read()
-    except IOError:
+    except OSError:
         import tkinter.messagebox as tkMessageBox
         tkMessageBox.showerror(title='File Load Error',
                                message='Unable to load file %r .' % filename,
diff --git a/Lib/imghdr.py b/Lib/imghdr.py
index 6ee45daab8..0cba063a9c 100644
--- a/Lib/imghdr.py
+++ b/Lib/imghdr.py
@@ -149,7 +149,7 @@ def testall(list, recursive, toplevel):
             sys.stdout.flush()
             try:
                 print(what(filename))
-            except IOError:
+            except OSError:
                 print('*** not found ***')
 
 if __name__ == '__main__':
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 3ea798d5bd..c71d67d9fd 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -915,7 +915,7 @@ class SourceLoader(_LoaderBasics):
         path = self.get_filename(fullname)
         try:
             source_bytes = self.get_data(path)
-        except IOError as exc:
+        except OSError as exc:
             raise ImportError("source not available through get_data()",
                               name=fullname) from exc
         readsource = _io.BytesIO(source_bytes).readline
@@ -961,7 +961,7 @@ class SourceLoader(_LoaderBasics):
                 source_mtime = int(st['mtime'])
                 try:
                     data = self.get_data(bytecode_path)
-                except IOError:
+                except OSError:
                     pass
                 else:
                     try:
diff --git a/Lib/inspect.py b/Lib/inspect.py
index 88f0ee2fc1..c389f6adc6 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -545,13 +545,13 @@ def findsource(object):
 
     The argument may be a module, class, method, function, traceback, frame,
     or code object.  The source code is returned as a list of all the lines
-    in the file and the line number indexes a line in that list.  An IOError
+    in the file and the line number indexes a line in that list.  An OSError
     is raised if the source code cannot be retrieved."""
 
     file = getfile(object)
     sourcefile = getsourcefile(object)
     if not sourcefile and file[0] + file[-1] != '<>':
-        raise IOError('source code not available')
+        raise OSError('source code not available')
     file = sourcefile if sourcefile else file
 
     module = getmodule(object, file)
@@ -560,7 +560,7 @@ def findsource(object):
     else:
         lines = linecache.getlines(file)
     if not lines:
-        raise IOError('could not get source code')
+        raise OSError('could not get source code')
 
     if ismodule(object):
         return lines, 0
@@ -586,7 +586,7 @@ def findsource(object):
             candidates.sort()
             return lines, candidates[0][1]
         else:
-            raise IOError('could not find class definition')
+            raise OSError('could not find class definition')
 
     if ismethod(object):
         object = object.__func__
@@ -598,14 +598,14 @@ def findsource(object):
         object = object.f_code
     if iscode(object):
         if not hasattr(object, 'co_firstlineno'):
-            raise IOError('could not find function definition')
+            raise OSError('could not find function definition')
         lnum = object.co_firstlineno - 1
         pat = re.compile(r'^(\s*def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
         while lnum > 0:
             if pat.match(lines[lnum]): break
             lnum = lnum - 1
         return lines, lnum
-    raise IOError('could not find code object')
+    raise OSError('could not find code object')
 
 def getcomments(object):
     """Get lines of comments immediately preceding an object's source code.
@@ -614,7 +614,7 @@ def getcomments(object):
     """
     try:
         lines, lnum = findsource(object)
-    except (IOError, TypeError):
+    except (OSError, TypeError):
         return None
 
     if ismodule(object):
@@ -710,7 +710,7 @@ def getsourcelines(object):
     The argument may be a module, class, method, function, traceback, frame,
     or code object.  The source code is returned as a list of the lines
     corresponding to the object and the line number indicates where in the
-    original source file the first line of code was found.  An IOError is
+    original source file the first line of code was found.  An OSError is
     raised if the source code cannot be retrieved."""
     lines, lnum = findsource(object)
 
@@ -722,7 +722,7 @@ def getsource(object):
 
     The argument may be a module, class, method, function, traceback, frame,
     or code object.  The source code is returned as a single string.  An
-    IOError is raised if the source code cannot be retrieved."""
+    OSError is raised if the source code cannot be retrieved."""
     lines, lnum = getsourcelines(object)
     return ''.join(lines)
 
@@ -1122,7 +1122,7 @@ def getframeinfo(frame, context=1):
         start = lineno - 1 - context//2
         try:
             lines, lnum = findsource(frame)
-        except IOError:
+        except OSError:
             lines = index = None
         else:
             start = max(start, 1)
diff --git a/Lib/io.py b/Lib/io.py
index bda4def3da..39878b8337 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -4,7 +4,7 @@ builtin open function is defined in this module.
 At the top of the I/O hierarchy is the abstract base class IOBase. It
 defines the basic interface to a stream. Note, however, that there is no
 separation between reading and writing to streams; implementations are
-allowed to raise an IOError if they do not support a given operation.
+allowed to raise an OSError if they do not support a given operation.
 
 Extending IOBase is RawIOBase which deals simply with the reading and
 writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide
diff --git a/Lib/lib2to3/pgen2/conv.py b/Lib/lib2to3/pgen2/conv.py
index bf49762ae4..ed0cac532e 100644
--- a/Lib/lib2to3/pgen2/conv.py
+++ b/Lib/lib2to3/pgen2/conv.py
@@ -60,7 +60,7 @@ class Converter(grammar.Grammar):
         """
         try:
             f = open(filename)
-        except IOError as err:
+        except OSError as err:
             print("Can't open %s: %s" % (filename, err))
             return False
         self.symbol2number = {}
@@ -111,7 +111,7 @@ class Converter(grammar.Grammar):
         """
         try:
             f = open(filename)
-        except IOError as err:
+        except OSError as err:
             print("Can't open %s: %s" % (filename, err))
             return False
         # The code below essentially uses f's iterator-ness!
diff --git a/Lib/lib2to3/pgen2/driver.py b/Lib/lib2to3/pgen2/driver.py
index 4c611c6640..3ccc69dcf6 100644
--- a/Lib/lib2to3/pgen2/driver.py
+++ b/Lib/lib2to3/pgen2/driver.py
@@ -123,7 +123,7 @@ def load_grammar(gt="Grammar.txt", gp=None,
             logger.info("Writing grammar tables to %s", gp)
             try:
                 g.dump(gp)
-            except IOError as e:
+            except OSError as e:
                 logger.info("Writing failed:"+str(e))
     else:
         g = grammar.Grammar()
diff --git a/Lib/lib2to3/refactor.py b/Lib/lib2to3/refactor.py
index 87f686e1e7..8100317871 100644
--- a/Lib/lib2to3/refactor.py
+++ b/Lib/lib2to3/refactor.py
@@ -326,7 +326,7 @@ class RefactoringTool(object):
         """
         try:
             f = open(filename, "rb")
-        except IOError as err:
+        except OSError as err:
             self.log_error("Can't open %s: %s", filename, err)
             return None, None
         try:
diff --git a/Lib/linecache.py b/Lib/linecache.py
index 71dc93dfb4..02a9eb5253 100644
--- a/Lib/linecache.py
+++ b/Lib/linecache.py
@@ -91,7 +91,7 @@ def updatecache(filename, module_globals=None):
             if name and get_source:
                 try:
                     data = get_source(name)
-                except (ImportError, IOError):
+                except (ImportError, OSError):
                     pass
                 else:
                     if data is None:
@@ -125,7 +125,7 @@ def updatecache(filename, module_globals=None):
     try:
         with tokenize.open(fullname) as fp:
             lines = fp.readlines()
-    except IOError:
+    except OSError:
         return []
     if lines and not lines[-1].endswith('\n'):
         lines[-1] += '\n'
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index 6f8b4fa67b..b8e7b377b3 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -896,7 +896,7 @@ class Handler(Filterer):
                     # couldn't find the right stack frame, for some reason
                     sys.stderr.write('Logged from file %s, line %s\n' % (
                                      record.filename, record.lineno))
-            except IOError: #pragma: no cover
+            except OSError: #pragma: no cover
                 pass    # see issue 5971
             finally:
                 del t, v, tb
@@ -1838,7 +1838,7 @@ def shutdown(handlerList=_handlerList):
                     h.acquire()
                     h.flush()
                     h.close()
-                except (IOError, ValueError):
+                except (OSError, ValueError):
                     # Ignore errors which might be caused
                     # because handlers have been closed but
                     # references to them are still around at
diff --git a/Lib/mailbox.py b/Lib/mailbox.py
index 01f35514a7..6d320eddeb 100644
--- a/Lib/mailbox.py
+++ b/Lib/mailbox.py
@@ -585,7 +585,7 @@ class _singlefileMailbox(Mailbox):
         Mailbox.__init__(self, path, factory, create)
         try:
             f = open(self._path, 'rb+')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 if create:
                     f = open(self._path, 'wb+')
@@ -988,7 +988,7 @@ class MH(Mailbox):
         path = os.path.join(self._path, str(key))
         try:
             f = open(path, 'rb+')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
             else:
@@ -1002,7 +1002,7 @@ class MH(Mailbox):
         path = os.path.join(self._path, str(key))
         try:
             f = open(path, 'rb+')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
             else:
@@ -1028,7 +1028,7 @@ class MH(Mailbox):
                 f = open(os.path.join(self._path, str(key)), 'rb+')
             else:
                 f = open(os.path.join(self._path, str(key)), 'rb')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
             else:
@@ -1055,7 +1055,7 @@ class MH(Mailbox):
                 f = open(os.path.join(self._path, str(key)), 'rb+')
             else:
                 f = open(os.path.join(self._path, str(key)), 'rb')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
             else:
@@ -1075,7 +1075,7 @@ class MH(Mailbox):
         """Return a file-like representation or raise a KeyError."""
         try:
             f = open(os.path.join(self._path, str(key)), 'rb')
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.ENOENT:
                 raise KeyError('No message with key: %s' % key)
             else:
@@ -2068,7 +2068,7 @@ def _lock_file(f, dotlock=True):
         if fcntl:
             try:
                 fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
-            except IOError as e:
+            except OSError as e:
                 if e.errno in (errno.EAGAIN, errno.EACCES, errno.EROFS):
                     raise ExternalClashError('lockf: lock unavailable: %s' %
                                              f.name)
@@ -2078,7 +2078,7 @@ def _lock_file(f, dotlock=True):
             try:
                 pre_lock = _create_temporary(f.name + '.lock')
                 pre_lock.close()
-            except IOError as e:
+            except OSError as e:
                 if e.errno in (errno.EACCES, errno.EROFS):
                     return  # Without write access, just skip dotlocking.
                 else:
diff --git a/Lib/mailcap.py b/Lib/mailcap.py
index 99f4958bf7..bd61b0b0ae 100644
--- a/Lib/mailcap.py
+++ b/Lib/mailcap.py
@@ -20,7 +20,7 @@ def getcaps():
     for mailcap in listmailcapfiles():
         try:
             fp = open(mailcap, 'r')
-        except IOError:
+        except OSError:
             continue
         morecaps = readmailcapfile(fp)
         fp.close()
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 40faf8c860..5aaa908087 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -359,7 +359,7 @@ def init(files=None):
 def read_mime_types(file):
     try:
         f = open(file)
-    except IOError:
+    except OSError:
         return None
     db = MimeTypes()
     db.readfp(f, True)
diff --git a/Lib/multiprocessing/connection.py b/Lib/multiprocessing/connection.py
index 391d6b2fbb..8b2be19ced 100644
--- a/Lib/multiprocessing/connection.py
+++ b/Lib/multiprocessing/connection.py
@@ -132,22 +132,22 @@ class _ConnectionBase:
 
     def _check_closed(self):
         if self._handle is None:
-            raise IOError("handle is closed")
+            raise OSError("handle is closed")
 
     def _check_readable(self):
         if not self._readable:
-            raise IOError("connection is write-only")
+            raise OSError("connection is write-only")
 
     def _check_writable(self):
         if not self._writable:
-            raise IOError("connection is read-only")
+            raise OSError("connection is read-only")
 
     def _bad_message_length(self):
         if self._writable:
             self._readable = False
         else:
             self.close()
-        raise IOError("bad message length")
+        raise OSError("bad message length")
 
     @property
     def closed(self):
@@ -317,7 +317,7 @@ if _winapi:
                             return f
                         elif err == _winapi.ERROR_MORE_DATA:
                             return self._get_more_data(ov, maxsize)
-                except IOError as e:
+                except OSError as e:
                     if e.winerror == _winapi.ERROR_BROKEN_PIPE:
                         raise EOFError
                     else:
@@ -383,7 +383,7 @@ class Connection(_ConnectionBase):
                 if remaining == size:
                     raise EOFError
                 else:
-                    raise IOError("got end of file during message")
+                    raise OSError("got end of file during message")
             buf.write(chunk)
             remaining -= n
         return buf
@@ -443,7 +443,7 @@ class Listener(object):
         Returns a `Connection` object.
         '''
         if self._listener is None:
-            raise IOError('listener is closed')
+            raise OSError('listener is closed')
         c = self._listener.accept()
         if self._authkey:
             deliver_challenge(c, self._authkey)
diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py
index 1ab147e29e..30ef771230 100644
--- a/Lib/multiprocessing/managers.py
+++ b/Lib/multiprocessing/managers.py
@@ -167,7 +167,7 @@ class Server(object):
         while True:
             try:
                 c = self.listener.accept()
-            except (OSError, IOError):
+            except OSError:
                 continue
             t = threading.Thread(target=self.handle_request, args=(c,))
             t.daemon = True
diff --git a/Lib/multiprocessing/pool.py b/Lib/multiprocessing/pool.py
index 7f73b441c2..c0aa717079 100644
--- a/Lib/multiprocessing/pool.py
+++ b/Lib/multiprocessing/pool.py
@@ -78,8 +78,8 @@ def worker(inqueue, outqueue, initializer=None, initargs=(), maxtasks=None):
     while maxtasks is None or (maxtasks and completed < maxtasks):
         try:
             task = get()
-        except (EOFError, IOError):
-            debug('worker got EOFError or IOError -- exiting')
+        except (EOFError, OSError):
+            debug('worker got EOFError or OSError -- exiting')
             break
 
         if task is None:
@@ -349,7 +349,7 @@ class Pool(object):
                     break
                 try:
                     put(task)
-                except IOError:
+                except OSError:
                     debug('could not put task on queue')
                     break
             else:
@@ -371,8 +371,8 @@ class Pool(object):
             debug('task handler sending sentinel to workers')
             for p in pool:
                 put(None)
-        except IOError:
-            debug('task handler got IOError when sending sentinels')
+        except OSError:
+            debug('task handler got OSError when sending sentinels')
 
         debug('task handler exiting')
 
@@ -383,8 +383,8 @@ class Pool(object):
         while 1:
             try:
                 task = get()
-            except (IOError, EOFError):
-                debug('result handler got EOFError/IOError -- exiting')
+            except (OSError, EOFError):
+                debug('result handler got EOFError/OSError -- exiting')
                 return
 
             if thread._state:
@@ -405,8 +405,8 @@ class Pool(object):
         while cache and thread._state != TERMINATE:
             try:
                 task = get()
-            except (IOError, EOFError):
-                debug('result handler got EOFError/IOError -- exiting')
+            except (OSError, EOFError):
+                debug('result handler got EOFError/OSError -- exiting')
                 return
 
             if task is None:
@@ -428,7 +428,7 @@ class Pool(object):
                     if not outqueue._reader.poll():
                         break
                     get()
-            except (IOError, EOFError):
+            except (OSError, EOFError):
                 pass
 
         debug('result handler exiting: len(cache)=%s, thread._state=%s',
diff --git a/Lib/netrc.py b/Lib/netrc.py
index c96db6f96a..7fe69ee458 100644
--- a/Lib/netrc.py
+++ b/Lib/netrc.py
@@ -25,7 +25,7 @@ class netrc:
             try:
                 file = os.path.join(os.environ['HOME'], ".netrc")
             except KeyError:
-                raise IOError("Could not find .netrc: $HOME is not set")
+                raise OSError("Could not find .netrc: $HOME is not set")
         self.hosts = {}
         self.macros = {}
         with open(file) as fp:
diff --git a/Lib/nntplib.py b/Lib/nntplib.py
index ffab2c20ed..01d4303f4d 100644
--- a/Lib/nntplib.py
+++ b/Lib/nntplib.py
@@ -947,7 +947,7 @@ class _NNTPBase:
                 if auth:
                     user = auth[0]
                     password = auth[2]
-        except IOError:
+        except OSError:
             pass
         # Perform NNTP authentication if needed.
         if not user:
diff --git a/Lib/nturl2path.py b/Lib/nturl2path.py
index 511dcec5d6..5a6d44a659 100644
--- a/Lib/nturl2path.py
+++ b/Lib/nturl2path.py
@@ -23,7 +23,7 @@ def url2pathname(url):
     comp = url.split('|')
     if len(comp) != 2 or comp[0][-1] not in string.ascii_letters:
         error = 'Bad URL: ' + url
-        raise IOError(error)
+        raise OSError(error)
     drive = comp[0][-1].upper()
     components = comp[1].split('/')
     path = drive + ':'
@@ -55,7 +55,7 @@ def pathname2url(p):
     comp = p.split(':')
     if len(comp) != 2 or len(comp[0]) > 1:
         error = 'Bad path: ' + p
-        raise IOError(error)
+        raise OSError(error)
 
     drive = urllib.parse.quote(comp[0].upper())
     components = comp[1].split('\\')
diff --git a/Lib/pdb.py b/Lib/pdb.py
index e6d7f8ff70..e5596e547e 100755
--- a/Lib/pdb.py
+++ b/Lib/pdb.py
@@ -92,7 +92,7 @@ def find_function(funcname, filename):
     cre = re.compile(r'def\s+%s\s*[(]' % re.escape(funcname))
     try:
         fp = open(filename)
-    except IOError:
+    except OSError:
         return None
     # consumer of this info expects the first line to be 1
     lineno = 1
@@ -170,12 +170,12 @@ class Pdb(bdb.Bdb, cmd.Cmd):
             try:
                 with open(os.path.join(envHome, ".pdbrc")) as rcFile:
                     self.rcLines.extend(rcFile)
-            except IOError:
+            except OSError:
                 pass
         try:
             with open(".pdbrc") as rcFile:
                 self.rcLines.extend(rcFile)
-        except IOError:
+        except OSError:
             pass
 
         self.commands = {} # associates a command list to breakpoint numbers
@@ -1241,7 +1241,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
         breaklist = self.get_file_breaks(filename)
         try:
             lines, lineno = getsourcelines(self.curframe)
-        except IOError as err:
+        except OSError as err:
             self.error(err)
             return
         self._print_lines(lines, lineno, breaklist, self.curframe)
@@ -1257,7 +1257,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
             return
         try:
             lines, lineno = getsourcelines(obj)
-        except (IOError, TypeError) as err:
+        except (OSError, TypeError) as err:
             self.error(err)
             return
         self._print_lines(lines, lineno)
diff --git a/Lib/pkgutil.py b/Lib/pkgutil.py
index 01eeefbedf..0f783dea1e 100644
--- a/Lib/pkgutil.py
+++ b/Lib/pkgutil.py
@@ -587,7 +587,7 @@ def extend_path(path, name):
         if os.path.isfile(pkgfile):
             try:
                 f = open(pkgfile)
-            except IOError as msg:
+            except OSError as msg:
                 sys.stderr.write("Can't open %s: %s\n" %
                                  (pkgfile, msg))
             else:
diff --git a/Lib/platform.py b/Lib/platform.py
index 143138dcfb..c54f7687ba 100755
--- a/Lib/platform.py
+++ b/Lib/platform.py
@@ -430,9 +430,6 @@ def _syscmd_ver(system='', release='', version='',
         except OSError as why:
             #print 'Command %s failed: %s' % (cmd,why)
             continue
-        except IOError as why:
-            #print 'Command %s failed: %s' % (cmd,why)
-            continue
         else:
             break
     else:
diff --git a/Lib/pstats.py b/Lib/pstats.py
index 6a77605e14..7cf000ffe0 100644
--- a/Lib/pstats.py
+++ b/Lib/pstats.py
@@ -612,7 +612,7 @@ if __name__ == '__main__':
             if line:
                 try:
                     self.stats = Stats(line)
-                except IOError as err:
+                except OSError as err:
                     print(err.args[1], file=self.stream)
                     return
                 except Exception as err:
diff --git a/Lib/pty.py b/Lib/pty.py
index 786ce04185..5fe53c1582 100644
--- a/Lib/pty.py
+++ b/Lib/pty.py
@@ -56,7 +56,7 @@ def _open_terminal():
     else:
         try:
             tty_name, master_fd = sgi._getpty(os.O_RDWR, 0o666, 0)
-        except IOError as msg:
+        except OSError as msg:
             raise OSError(msg)
         return master_fd, tty_name
     for x in 'pqrstuvwxyzPQRST':
@@ -83,7 +83,7 @@ def slave_open(tty_name):
     try:
         ioctl(result, I_PUSH, "ptem")
         ioctl(result, I_PUSH, "ldterm")
-    except IOError:
+    except OSError:
         pass
     return result
 
@@ -173,7 +173,7 @@ def spawn(argv, master_read=_read, stdin_read=_read):
         restore = 0
     try:
         _copy(master_fd, master_read, stdin_read)
-    except (IOError, OSError):
+    except OSError:
         if restore:
             tty.tcsetattr(STDIN_FILENO, tty.TCSAFLUSH, mode)
 
diff --git a/Lib/py_compile.py b/Lib/py_compile.py
index 62d69ad448..3cb46d0736 100644
--- a/Lib/py_compile.py
+++ b/Lib/py_compile.py
@@ -173,7 +173,7 @@ def main(args=None):
             except PyCompileError as error:
                 rv = 1
                 sys.stderr.write("%s\n" % error.msg)
-            except IOError as error:
+            except OSError as error:
                 rv = 1
                 sys.stderr.write("%s\n" % error)
     else:
diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 490eb210d2..81fcfd9f0c 100755
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -223,7 +223,7 @@ def synopsis(filename, cache={}):
     if lastupdate is None or lastupdate < mtime:
         try:
             file = tokenize.open(filename)
-        except IOError:
+        except OSError:
             # module can't be opened, so skip it
             return None
         binary_suffixes = importlib.machinery.BYTECODE_SUFFIXES[:]
@@ -1419,7 +1419,7 @@ def pipepager(text, cmd):
     try:
         pipe.write(text)
         pipe.close()
-    except IOError:
+    except OSError:
         pass # Ignore broken pipes caused by quitting the pager program.
 
 def tempfilepager(text, cmd):
diff --git a/Lib/quopri.py b/Lib/quopri.py
index 3d0f0ac078..e5bd010d5b 100755
--- a/Lib/quopri.py
+++ b/Lib/quopri.py
@@ -223,7 +223,7 @@ def main():
         else:
             try:
                 fp = open(file, "rb")
-            except IOError as msg:
+            except OSError as msg:
                 sys.stderr.write("%s: can't open (%s)\n" % (file, msg))
                 sts = 1
                 continue
diff --git a/Lib/site.py b/Lib/site.py
index 982dbc89a5..c4c8ea040e 100644
--- a/Lib/site.py
+++ b/Lib/site.py
@@ -153,7 +153,7 @@ def addpackage(sitedir, name, known_paths):
     fullname = os.path.join(sitedir, name)
     try:
         f = open(fullname, "r")
-    except IOError:
+    except OSError:
         return
     with f:
         for n, line in enumerate(f):
@@ -388,7 +388,7 @@ class _Printer(object):
                     data = fp.read()
                     fp.close()
                     break
-                except IOError:
+                except OSError:
                     pass
             if data:
                 break
diff --git a/Lib/sndhdr.py b/Lib/sndhdr.py
index 9f5dcc90d4..0a2fa8dca2 100644
--- a/Lib/sndhdr.py
+++ b/Lib/sndhdr.py
@@ -11,7 +11,7 @@ The return tuple contains the following items, in this order:
 - number of bits/sample, or 'U' for U-LAW, or 'A' for A-LAW
 
 If the file doesn't have a recognizable type, it returns None.
-If the file can't be opened, IOError is raised.
+If the file can't be opened, OSError is raised.
 
 To compute the total time, divide the number of frames by the
 sampling rate (a frame contains a sample for each channel).
@@ -230,7 +230,7 @@ def testall(list, recursive, toplevel):
             sys.stdout.flush()
             try:
                 print(what(filename))
-            except IOError:
+            except OSError:
                 print('*** not found ***')
 
 if __name__ == '__main__':
diff --git a/Lib/socket.py b/Lib/socket.py
index d4f1b65e46..da0c39a8ae 100644
--- a/Lib/socket.py
+++ b/Lib/socket.py
@@ -291,7 +291,7 @@ class SocketIO(io.RawIOBase):
         self._checkClosed()
         self._checkReadable()
         if self._timeout_occurred:
-            raise IOError("cannot read from timed out object")
+            raise OSError("cannot read from timed out object")
         while True:
             try:
                 return self._sock.recv_into(b)
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index fd5104891c..c66bd63621 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -897,7 +897,7 @@ class Popen(object):
                 if input:
                     try:
                         self.stdin.write(input)
-                    except IOError as e:
+                    except OSError as e:
                         if e.errno != errno.EPIPE and e.errno != errno.EINVAL:
                             raise
                 self.stdin.close()
@@ -1152,7 +1152,7 @@ class Popen(object):
                 if input is not None:
                     try:
                         self.stdin.write(input)
-                    except IOError as e:
+                    except OSError as e:
                         if e.errno != errno.EPIPE:
                             raise
                 self.stdin.close()
diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
index 295a0a6ecd..a98cc71533 100644
--- a/Lib/sysconfig.py
+++ b/Lib/sysconfig.py
@@ -349,21 +349,21 @@ def _generate_posix_vars():
     makefile = get_makefile_filename()
     try:
         _parse_makefile(makefile, vars)
-    except IOError as e:
+    except OSError as e:
         msg = "invalid Python installation: unable to open %s" % makefile
         if hasattr(e, "strerror"):
             msg = msg + " (%s)" % e.strerror
-        raise IOError(msg)
+        raise OSError(msg)
     # load the installed pyconfig.h:
     config_h = get_config_h_filename()
     try:
         with open(config_h) as f:
             parse_config_h(f, vars)
-    except IOError as e:
+    except OSError as e:
         msg = "invalid Python installation: unable to open %s" % config_h
         if hasattr(e, "strerror"):
             msg = msg + " (%s)" % e.strerror
-        raise IOError(msg)
+        raise OSError(msg)
     # On AIX, there are wrong paths to the linker scripts in the Makefile
     # -- these paths are relative to the Python source, but when installed
     # the scripts are in another directory.
diff --git a/Lib/tabnanny.py b/Lib/tabnanny.py
index 5b9b444c1a..46e0f56a39 100755
--- a/Lib/tabnanny.py
+++ b/Lib/tabnanny.py
@@ -95,7 +95,7 @@ def check(file):
 
     try:
         f = tokenize.open(file)
-    except IOError as msg:
+    except OSError as msg:
         errprint("%r: I/O Error: %s" % (file, msg))
         return
 
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index a0f132e20d..ffa732749d 100644
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -264,13 +264,13 @@ def copyfileobj(src, dst, length=None):
     for b in range(blocks):
         buf = src.read(BUFSIZE)
         if len(buf) < BUFSIZE:
-            raise IOError("end of file reached")
+            raise OSError("end of file reached")
         dst.write(buf)
 
     if remainder != 0:
         buf = src.read(remainder)
         if len(buf) < remainder:
-            raise IOError("end of file reached")
+            raise OSError("end of file reached")
         dst.write(buf)
     return
 
@@ -399,7 +399,7 @@ class _Stream:
                 if mode == "r":
                     self.dbuf = b""
                     self.cmp = bz2.BZ2Decompressor()
-                    self.exception = IOError
+                    self.exception = OSError
                 else:
                     self.cmp = bz2.BZ2Compressor()
 
@@ -1631,7 +1631,7 @@ class TarFile(object):
         try:
             fileobj = gzip.GzipFile(name, mode + "b", compresslevel, fileobj)
             t = cls.taropen(name, mode, fileobj, **kwargs)
-        except IOError:
+        except OSError:
             if not extfileobj and fileobj is not None:
                 fileobj.close()
             if fileobj is None:
@@ -1662,7 +1662,7 @@ class TarFile(object):
 
         try:
             t = cls.taropen(name, mode, fileobj, **kwargs)
-        except (IOError, EOFError):
+        except (OSError, EOFError):
             fileobj.close()
             raise ReadError("not a bzip2 file")
         t._extfileobj = False
@@ -2322,9 +2322,9 @@ class TarFile(object):
            corresponds to TarFile's mode.
         """
         if self.closed:
-            raise IOError("%s is closed" % self.__class__.__name__)
+            raise OSError("%s is closed" % self.__class__.__name__)
         if mode is not None and self.mode not in mode:
-            raise IOError("bad operation for mode %r" % self.mode)
+            raise OSError("bad operation for mode %r" % self.mode)
 
     def _find_link_target(self, tarinfo):
         """Find the target member of a symlink or hardlink member in the
diff --git a/Lib/test/fork_wait.py b/Lib/test/fork_wait.py
index 88527df25e..19b54ec736 100644
--- a/Lib/test/fork_wait.py
+++ b/Lib/test/fork_wait.py
@@ -28,7 +28,7 @@ class ForkWait(unittest.TestCase):
             self.alive[id] = os.getpid()
             try:
                 time.sleep(SHORTSLEEP)
-            except IOError:
+            except OSError:
                 pass
 
     def wait_impl(self, cpid):
diff --git a/Lib/test/multibytecodec_support.py b/Lib/test/multibytecodec_support.py
index 26bac7be10..dcaae7b95c 100644
--- a/Lib/test/multibytecodec_support.py
+++ b/Lib/test/multibytecodec_support.py
@@ -282,7 +282,7 @@ class TestBase_Mapping(unittest.TestCase):
         unittest.TestCase.__init__(self, *args, **kw)
         try:
             self.open_mapping_file().close() # test it to report the error early
-        except (IOError, HTTPException):
+        except (OSError, HTTPException):
             self.skipTest("Could not retrieve "+self.mapfileurl)
 
     def open_mapping_file(self):
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 5d9d82d673..4e6064cf90 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -506,7 +506,7 @@ def main(tests=None, testdir=None, verbose=0, quiet=False,
             next_test = fp.read().strip()
             tests = [next_test]
             fp.close()
-        except IOError:
+        except OSError:
             pass
 
     if fromfile:
diff --git a/Lib/test/sortperf.py b/Lib/test/sortperf.py
index a370ed90ee..90722f7abc 100644
--- a/Lib/test/sortperf.py
+++ b/Lib/test/sortperf.py
@@ -22,7 +22,7 @@ def randfloats(n):
     fn = os.path.join(td, "rr%06d" % n)
     try:
         fp = open(fn, "rb")
-    except IOError:
+    except OSError:
         r = random.random
         result = [r() for i in range(n)]
         try:
@@ -37,7 +37,7 @@ def randfloats(n):
                         os.unlink(fn)
                     except OSError:
                         pass
-        except IOError as msg:
+        except OSError as msg:
             print("can't write", fn, ":", msg)
     else:
         result = marshal.load(fp)
diff --git a/Lib/test/support.py b/Lib/test/support.py
index d776b99627..dab0f1b90b 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -1097,9 +1097,9 @@ class TransientResource(object):
 # Context managers that raise ResourceDenied when various issues
 # with the Internet connection manifest themselves as exceptions.
 # XXX deprecate these and use transient_internet() instead
-time_out = TransientResource(IOError, errno=errno.ETIMEDOUT)
+time_out = TransientResource(OSError, errno=errno.ETIMEDOUT)
 socket_peer_reset = TransientResource(OSError, errno=errno.ECONNRESET)
-ioerror_peer_reset = TransientResource(IOError, errno=errno.ECONNRESET)
+ioerror_peer_reset = TransientResource(OSError, errno=errno.ECONNRESET)
 
 
 @contextlib.contextmanager
@@ -1145,17 +1145,17 @@ def transient_internet(resource_name, *, timeout=30.0, errnos=()):
         if timeout is not None:
             socket.setdefaulttimeout(timeout)
         yield
-    except IOError as err:
+    except OSError as err:
         # urllib can wrap original socket errors multiple times (!), we must
         # unwrap to get at the original error.
         while True:
             a = err.args
-            if len(a) >= 1 and isinstance(a[0], IOError):
+            if len(a) >= 1 and isinstance(a[0], OSError):
                 err = a[0]
             # The error can also be wrapped as args[1]:
             #    except socket.error as msg:
-            #        raise IOError('socket error', msg).with_traceback(sys.exc_info()[2])
-            elif len(a) >= 2 and isinstance(a[1], IOError):
+            #        raise OSError('socket error', msg).with_traceback(sys.exc_info()[2])
+            elif len(a) >= 2 and isinstance(a[1], OSError):
                 err = a[1]
             else:
                 break
diff --git a/Lib/test/test_array.py b/Lib/test/test_array.py
index 544c2cefa2..9c19b57993 100755
--- a/Lib/test/test_array.py
+++ b/Lib/test/test_array.py
@@ -355,12 +355,12 @@ class BaseTest(unittest.TestCase):
             support.unlink(support.TESTFN)
 
     def test_fromfile_ioerror(self):
-        # Issue #5395: Check if fromfile raises a proper IOError
+        # Issue #5395: Check if fromfile raises a proper OSError
         # instead of EOFError.
         a = array.array(self.typecode)
         f = open(support.TESTFN, 'wb')
         try:
-            self.assertRaises(IOError, a.fromfile, f, len(self.example))
+            self.assertRaises(OSError, a.fromfile, f, len(self.example))
         finally:
             f.close()
             support.unlink(support.TESTFN)
diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index 24a18138fe..fb2f782886 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -253,8 +253,8 @@ class BZ2FileTest(BaseTest):
             bz2f.write(b"abc")
 
         with BZ2File(self.filename, "r") as bz2f:
-            self.assertRaises(IOError, bz2f.write, b"a")
-            self.assertRaises(IOError, bz2f.writelines, [b"a"])
+            self.assertRaises(OSError, bz2f.write, b"a")
+            self.assertRaises(OSError, bz2f.writelines, [b"a"])
 
     def testAppend(self):
         with BZ2File(self.filename, "w") as bz2f:
@@ -429,7 +429,7 @@ class BZ2FileTest(BaseTest):
             del o
 
     def testOpenNonexistent(self):
-        self.assertRaises(IOError, BZ2File, "/non/existent")
+        self.assertRaises(OSError, BZ2File, "/non/existent")
 
     def testReadlinesNoNewline(self):
         # Issue #1191043: readlines() fails on a file containing no newline.
diff --git a/Lib/test/test_csv.py b/Lib/test/test_csv.py
index 96f8aa7ee1..3dc3836015 100644
--- a/Lib/test/test_csv.py
+++ b/Lib/test/test_csv.py
@@ -136,12 +136,12 @@ class Test_Csv(unittest.TestCase):
                 return 10;
             def __getitem__(self, i):
                 if i > 2:
-                    raise IOError
-        self.assertRaises(IOError, self._write_test, BadList(), '')
+                    raise OSError
+        self.assertRaises(OSError, self._write_test, BadList(), '')
         class BadItem:
             def __str__(self):
-                raise IOError
-        self.assertRaises(IOError, self._write_test, [BadItem()], '')
+                raise OSError
+        self.assertRaises(OSError, self._write_test, [BadItem()], '')
 
     def test_write_bigfield(self):
         # This exercises the buffer realloc functionality
@@ -186,9 +186,9 @@ class Test_Csv(unittest.TestCase):
     def test_writerows(self):
         class BrokenFile:
             def write(self, buf):
-                raise IOError
+                raise OSError
         writer = csv.writer(BrokenFile())
-        self.assertRaises(IOError, writer.writerows, [['a']])
+        self.assertRaises(OSError, writer.writerows, [['a']])
 
         with TemporaryFile("w+", newline='') as fileobj:
             writer = csv.writer(fileobj)
diff --git a/Lib/test/test_dbm.py b/Lib/test/test_dbm.py
index 02df7e3cab..95301bff10 100644
--- a/Lib/test/test_dbm.py
+++ b/Lib/test/test_dbm.py
@@ -57,7 +57,7 @@ class AnyDBMTestCase(unittest.TestCase):
         return keys
 
     def test_error(self):
-        self.assertTrue(issubclass(self.module.error, IOError))
+        self.assertTrue(issubclass(self.module.error, OSError))
 
     def test_anydbm_not_existing(self):
         self.assertRaises(dbm.error, dbm.open, _fname)
diff --git a/Lib/test/test_email/torture_test.py b/Lib/test/test_email/torture_test.py
index 544b1bbb39..19cf64f0c7 100644
--- a/Lib/test/test_email/torture_test.py
+++ b/Lib/test/test_email/torture_test.py
@@ -27,7 +27,7 @@ def openfile(filename):
 # Prevent this test from running in the Python distro
 try:
     openfile('crispin-torture.txt')
-except IOError:
+except OSError:
     raise TestSkipped
 
 
diff --git a/Lib/test/test_epoll.py b/Lib/test/test_epoll.py
index a3d4e2d9e2..7077a70057 100644
--- a/Lib/test/test_epoll.py
+++ b/Lib/test/test_epoll.py
@@ -33,7 +33,7 @@ if not hasattr(select, "epoll"):
 
 try:
     select.epoll()
-except IOError as e:
+except OSError as e:
     if e.errno == errno.ENOSYS:
         raise unittest.SkipTest("kernel doesn't support epoll()")
     raise
@@ -122,12 +122,12 @@ class TestEPoll(unittest.TestCase):
             # ValueError: file descriptor cannot be a negative integer (-1)
             self.assertRaises(ValueError, ep.register, -1,
                 select.EPOLLIN | select.EPOLLOUT)
-            # IOError: [Errno 9] Bad file descriptor
-            self.assertRaises(IOError, ep.register, 10000,
+            # OSError: [Errno 9] Bad file descriptor
+            self.assertRaises(OSError, ep.register, 10000,
                 select.EPOLLIN | select.EPOLLOUT)
             # registering twice also raises an exception
             ep.register(server, select.EPOLLIN | select.EPOLLOUT)
-            self.assertRaises(IOError, ep.register, server,
+            self.assertRaises(OSError, ep.register, server,
                 select.EPOLLIN | select.EPOLLOUT)
         finally:
             ep.close()
@@ -149,7 +149,7 @@ class TestEPoll(unittest.TestCase):
         ep.close()
         try:
             ep2.poll(1, 4)
-        except IOError as e:
+        except OSError as e:
             self.assertEqual(e.args[0], errno.EBADF, e)
         else:
             self.fail("epoll on closed fd didn't raise EBADF")
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
index 6fa1f5bfa1..2f39d4b864 100644
--- a/Lib/test/test_exceptions.py
+++ b/Lib/test/test_exceptions.py
@@ -244,16 +244,16 @@ class ExceptionTests(unittest.TestCase):
                 {'args' : ('foo', 1)}),
             (SystemExit, ('foo',),
                 {'args' : ('foo',), 'code' : 'foo'}),
-            (IOError, ('foo',),
+            (OSError, ('foo',),
                 {'args' : ('foo',), 'filename' : None,
                  'errno' : None, 'strerror' : None}),
-            (IOError, ('foo', 'bar'),
+            (OSError, ('foo', 'bar'),
                 {'args' : ('foo', 'bar'), 'filename' : None,
                  'errno' : 'foo', 'strerror' : 'bar'}),
-            (IOError, ('foo', 'bar', 'baz'),
+            (OSError, ('foo', 'bar', 'baz'),
                 {'args' : ('foo', 'bar'), 'filename' : 'baz',
                  'errno' : 'foo', 'strerror' : 'bar'}),
-            (IOError, ('foo', 'bar', 'baz', 'quux'),
+            (OSError, ('foo', 'bar', 'baz', 'quux'),
                 {'args' : ('foo', 'bar', 'baz', 'quux')}),
             (OSError, ('errnoStr', 'strErrorStr', 'filenameStr'),
                 {'args' : ('errnoStr', 'strErrorStr'),
diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index bb0da792f5..d5eca2bb77 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -87,7 +87,7 @@ class AutoFileTests(unittest.TestCase):
         self.assertTrue(not f.closed)
 
         if hasattr(f, "readinto"):
-            self.assertRaises((IOError, TypeError), f.readinto, "")
+            self.assertRaises((OSError, TypeError), f.readinto, "")
         f.close()
         self.assertTrue(f.closed)
 
@@ -126,7 +126,7 @@ class AutoFileTests(unittest.TestCase):
             self.assertEqual(self.f.__exit__(*sys.exc_info()), None)
 
     def testReadWhenWriting(self):
-        self.assertRaises(IOError, self.f.read)
+        self.assertRaises(OSError, self.f.read)
 
 class CAutoFileTests(AutoFileTests):
     open = io.open
@@ -151,12 +151,12 @@ class OtherFileTests(unittest.TestCase):
     def testStdin(self):
         # This causes the interpreter to exit on OSF1 v5.1.
         if sys.platform != 'osf1V5':
-            self.assertRaises((IOError, ValueError), sys.stdin.seek, -1)
+            self.assertRaises((OSError, ValueError), sys.stdin.seek, -1)
         else:
             print((
                 '  Skipping sys.stdin.seek(-1), it may crash the interpreter.'
                 ' Test manually.'), file=sys.__stdout__)
-        self.assertRaises((IOError, ValueError), sys.stdin.truncate)
+        self.assertRaises((OSError, ValueError), sys.stdin.truncate)
 
     def testBadModeArgument(self):
         # verify that we get a sensible error message for bad mode argument
@@ -187,7 +187,7 @@ class OtherFileTests(unittest.TestCase):
                 d = int(f.read().decode("ascii"))
                 f.close()
                 f.close()
-            except IOError as msg:
+            except OSError as msg:
                 self.fail('error setting buffer size %d: %s' % (s, str(msg)))
             self.assertEqual(d, s)
 
diff --git a/Lib/test/test_fileinput.py b/Lib/test/test_fileinput.py
index 1e70641150..c42e3e8930 100644
--- a/Lib/test/test_fileinput.py
+++ b/Lib/test/test_fileinput.py
@@ -275,8 +275,8 @@ class FileInputTests(unittest.TestCase):
         try:
             t1 = writeTmp(1, [""])
             with FileInput(files=t1) as fi:
-                raise IOError
-        except IOError:
+                raise OSError
+        except OSError:
             self.assertEqual(fi._files, ())
         finally:
             remove_tempfiles(t1)
diff --git a/Lib/test/test_fileio.py b/Lib/test/test_fileio.py
index 9615c3af0c..0badf51f80 100644
--- a/Lib/test/test_fileio.py
+++ b/Lib/test/test_fileio.py
@@ -144,16 +144,16 @@ class AutoFileTests(unittest.TestCase):
         # Unix calls dircheck() and returns "[Errno 21]: Is a directory"
         try:
             _FileIO('.', 'r')
-        except IOError as e:
+        except OSError as e:
             self.assertNotEqual(e.errno, 0)
             self.assertEqual(e.filename, ".")
         else:
-            self.fail("Should have raised IOError")
+            self.fail("Should have raised OSError")
 
     @unittest.skipIf(os.name == 'nt', "test only works on a POSIX-like system")
     def testOpenDirFD(self):
         fd = os.open('.', os.O_RDONLY)
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             _FileIO(fd, 'r')
         os.close(fd)
         self.assertEqual(cm.exception.errno, errno.EISDIR)
@@ -171,7 +171,7 @@ class AutoFileTests(unittest.TestCase):
             finally:
                 try:
                     self.f.close()
-                except IOError:
+                except OSError:
                     pass
         return wrapper
 
@@ -183,14 +183,14 @@ class AutoFileTests(unittest.TestCase):
             os.close(f.fileno())
             try:
                 func(self, f)
-            except IOError as e:
+            except OSError as e:
                 self.assertEqual(e.errno, errno.EBADF)
             else:
-                self.fail("Should have raised IOError")
+                self.fail("Should have raised OSError")
             finally:
                 try:
                     self.f.close()
-                except IOError:
+                except OSError:
                     pass
         return wrapper
 
@@ -237,7 +237,7 @@ class AutoFileTests(unittest.TestCase):
     def ReopenForRead(self):
         try:
             self.f.close()
-        except IOError:
+        except OSError:
             pass
         self.f = _FileIO(TESTFN, 'r')
         os.close(self.f.fileno())
@@ -346,7 +346,7 @@ class OtherFileTests(unittest.TestCase):
         self.assertRaises(OSError, _FileIO, make_bad_fd())
         if sys.platform == 'win32':
             import msvcrt
-            self.assertRaises(IOError, msvcrt.get_osfhandle, make_bad_fd())
+            self.assertRaises(OSError, msvcrt.get_osfhandle, make_bad_fd())
 
     def testBadModeArgument(self):
         # verify that we get a sensible error message for bad mode argument
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index 861d670608..4dfc457010 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -482,7 +482,7 @@ class TestFTPClass(TestCase):
 
     def test_all_errors(self):
         exceptions = (ftplib.error_reply, ftplib.error_temp, ftplib.error_perm,
-                      ftplib.error_proto, ftplib.Error, IOError, EOFError)
+                      ftplib.error_proto, ftplib.Error, OSError, EOFError)
         for x in exceptions:
             try:
                 raise x('exception not included in all_errors set')
@@ -721,7 +721,7 @@ class TestFTPClass(TestCase):
                                 source_address=(HOST, port))
             self.assertEqual(self.client.sock.getsockname()[1], port)
             self.client.quit()
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.EADDRINUSE:
                 self.skipTest("couldn't bind to port %d" % port)
             raise
@@ -732,7 +732,7 @@ class TestFTPClass(TestCase):
         try:
             with self.client.transfercmd('list') as sock:
                 self.assertEqual(sock.getsockname()[1], port)
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.EADDRINUSE:
                 self.skipTest("couldn't bind to port %d" % port)
             raise
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
index 06776de8be..0e15fa314a 100644
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -114,7 +114,7 @@ class SimpleIMAPHandler(socketserver.StreamRequestHandler):
                         # Naked sockets return empty strings..
                         return
                     line += part
-                except IOError:
+                except OSError:
                     # ..but SSLSockets raise exceptions.
                     return
                 if line.endswith(b'\r\n'):
diff --git a/Lib/test/test_importlib/source/test_abc_loader.py b/Lib/test/test_importlib/source/test_abc_loader.py
index cce7b07098..718a548921 100644
--- a/Lib/test/test_importlib/source/test_abc_loader.py
+++ b/Lib/test/test_importlib/source/test_abc_loader.py
@@ -59,7 +59,7 @@ class SourceLoaderMock(SourceOnlyLoaderMock):
         elif path == self.bytecode_path:
             return self.bytecode
         else:
-            raise IOError
+            raise OSError
 
     def path_stats(self, path):
         assert path == self.path
@@ -125,12 +125,12 @@ class SourceOnlyLoaderTests(SourceLoaderTestHarness):
 
     def test_get_source(self):
         # Verify the source code is returned as a string.
-        # If an IOError is raised by get_data then raise ImportError.
+        # If an OSError is raised by get_data then raise ImportError.
         expected_source = self.loader.source.decode('utf-8')
         self.assertEqual(self.loader.get_source(self.name), expected_source)
-        def raise_IOError(path):
-            raise IOError
-        self.loader.get_data = raise_IOError
+        def raise_OSError(path):
+            raise OSError
+        self.loader.get_data = raise_OSError
         with self.assertRaises(ImportError) as cm:
             self.loader.get_source(self.name)
         self.assertEqual(cm.exception.name, self.name)
@@ -216,7 +216,7 @@ class SourceLoaderBytecodeTests(SourceLoaderTestHarness):
         # If no bytecode exists then move on to the source.
         self.loader.bytecode_path = "<does not exist>"
         # Sanity check
-        with self.assertRaises(IOError):
+        with self.assertRaises(OSError):
             bytecode_path = imp.cache_from_source(self.path)
             self.loader.get_data(bytecode_path)
         code_object = self.loader.get_code(self.name)
@@ -265,7 +265,7 @@ class SourceLoaderBytecodeTests(SourceLoaderTestHarness):
             self.loader.__class__.set_data = original_set_data
 
     def test_set_data_raises_exceptions(self):
-        # Raising NotImplementedError or IOError is okay for set_data.
+        # Raising NotImplementedError or OSError is okay for set_data.
         def raise_exception(exc):
             def closure(*args, **kwargs):
                 raise exc
diff --git a/Lib/test/test_importlib/source/test_file_loader.py b/Lib/test/test_importlib/source/test_file_loader.py
index 90f9d30129..dd28e8fd5d 100644
--- a/Lib/test/test_importlib/source/test_file_loader.py
+++ b/Lib/test/test_importlib/source/test_file_loader.py
@@ -407,7 +407,7 @@ class SourceLoaderBadBytecodeTest(BadBytecodeTest):
             os.chmod(bytecode_path,
                         stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
             try:
-                # Should not raise IOError!
+                # Should not raise OSError!
                 self.import_(mapping['_temp'], '_temp')
             finally:
                 # Make writable for eventual clean-up.
diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 80db03bf00..0ab414d9fa 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -401,14 +401,14 @@ class TestBuggyCases(GetSourceBase):
             unicodedata.__file__[-4:] in (".pyc", ".pyo"),
         "unicodedata is not an external binary module")
     def test_findsource_binary(self):
-        self.assertRaises(IOError, inspect.getsource, unicodedata)
-        self.assertRaises(IOError, inspect.findsource, unicodedata)
+        self.assertRaises(OSError, inspect.getsource, unicodedata)
+        self.assertRaises(OSError, inspect.findsource, unicodedata)
 
     def test_findsource_code_in_linecache(self):
         lines = ["x=1"]
         co = compile(lines[0], "_dynamically_created_file", "exec")
-        self.assertRaises(IOError, inspect.findsource, co)
-        self.assertRaises(IOError, inspect.getsource, co)
+        self.assertRaises(OSError, inspect.findsource, co)
+        self.assertRaises(OSError, inspect.getsource, co)
         linecache.cache[co.co_filename] = (1, None, lines, co.co_filename)
         try:
             self.assertEqual(inspect.findsource(co), (lines,0))
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index 28d3e0f4ac..7906060e7b 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -164,7 +164,7 @@ class CloseFailureIO(MockRawIO):
     def close(self):
         if not self.closed:
             self.closed = 1
-            raise IOError
+            raise OSError
 
 class CCloseFailureIO(CloseFailureIO, io.RawIOBase):
     pass
@@ -600,9 +600,9 @@ class IOTest(unittest.TestCase):
     def test_flush_error_on_close(self):
         f = self.open(support.TESTFN, "wb", buffering=0)
         def bad_flush():
-            raise IOError()
+            raise OSError()
         f.flush = bad_flush
-        self.assertRaises(IOError, f.close) # exception not swallowed
+        self.assertRaises(OSError, f.close) # exception not swallowed
         self.assertTrue(f.closed)
 
     def test_multi_close(self):
@@ -761,7 +761,7 @@ class CommonBufferedTests:
         if s:
             # The destructor *may* have printed an unraisable error, check it
             self.assertEqual(len(s.splitlines()), 1)
-            self.assertTrue(s.startswith("Exception IOError: "), s)
+            self.assertTrue(s.startswith("Exception OSError: "), s)
             self.assertTrue(s.endswith(" ignored"), s)
 
     def test_repr(self):
@@ -777,22 +777,22 @@ class CommonBufferedTests:
     def test_flush_error_on_close(self):
         raw = self.MockRawIO()
         def bad_flush():
-            raise IOError()
+            raise OSError()
         raw.flush = bad_flush
         b = self.tp(raw)
-        self.assertRaises(IOError, b.close) # exception not swallowed
+        self.assertRaises(OSError, b.close) # exception not swallowed
         self.assertTrue(b.closed)
 
     def test_close_error_on_close(self):
         raw = self.MockRawIO()
         def bad_flush():
-            raise IOError('flush')
+            raise OSError('flush')
         def bad_close():
-            raise IOError('close')
+            raise OSError('close')
         raw.close = bad_close
         b = self.tp(raw)
         b.flush = bad_flush
-        with self.assertRaises(IOError) as err: # exception not swallowed
+        with self.assertRaises(OSError) as err: # exception not swallowed
             b.close()
         self.assertEqual(err.exception.args, ('close',))
         self.assertEqual(err.exception.__context__.args, ('flush',))
@@ -1014,8 +1014,8 @@ class BufferedReaderTest(unittest.TestCase, CommonBufferedTests):
     def test_misbehaved_io(self):
         rawio = self.MisbehavedRawIO((b"abc", b"d", b"efg"))
         bufio = self.tp(rawio)
-        self.assertRaises(IOError, bufio.seek, 0)
-        self.assertRaises(IOError, bufio.tell)
+        self.assertRaises(OSError, bufio.seek, 0)
+        self.assertRaises(OSError, bufio.tell)
 
     def test_no_extraneous_read(self):
         # Issue #9550; when the raw IO object has satisfied the read request,
@@ -1066,7 +1066,7 @@ class CBufferedReaderTest(BufferedReaderTest, SizeofTest):
         bufio = self.tp(rawio)
         # _pyio.BufferedReader seems to implement reading different, so that
         # checking this is not so easy.
-        self.assertRaises(IOError, bufio.read, 10)
+        self.assertRaises(OSError, bufio.read, 10)
 
     def test_garbage_collection(self):
         # C BufferedReader objects are collected.
@@ -1313,9 +1313,9 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
     def test_misbehaved_io(self):
         rawio = self.MisbehavedRawIO()
         bufio = self.tp(rawio, 5)
-        self.assertRaises(IOError, bufio.seek, 0)
-        self.assertRaises(IOError, bufio.tell)
-        self.assertRaises(IOError, bufio.write, b"abcdef")
+        self.assertRaises(OSError, bufio.seek, 0)
+        self.assertRaises(OSError, bufio.tell)
+        self.assertRaises(OSError, bufio.write, b"abcdef")
 
     def test_max_buffer_size_removal(self):
         with self.assertRaises(TypeError):
@@ -1324,11 +1324,11 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
     def test_write_error_on_close(self):
         raw = self.MockRawIO()
         def bad_write(b):
-            raise IOError()
+            raise OSError()
         raw.write = bad_write
         b = self.tp(raw)
         b.write(b'spam')
-        self.assertRaises(IOError, b.close) # exception not swallowed
+        self.assertRaises(OSError, b.close) # exception not swallowed
         self.assertTrue(b.closed)
 
 
@@ -1393,14 +1393,14 @@ class BufferedRWPairTest(unittest.TestCase):
             def readable(self):
                 return False
 
-        self.assertRaises(IOError, self.tp, NotReadable(), self.MockRawIO())
+        self.assertRaises(OSError, self.tp, NotReadable(), self.MockRawIO())
 
     def test_constructor_with_not_writeable(self):
         class NotWriteable(MockRawIO):
             def writable(self):
                 return False
 
-        self.assertRaises(IOError, self.tp, self.MockRawIO(), NotWriteable())
+        self.assertRaises(OSError, self.tp, self.MockRawIO(), NotWriteable())
 
     def test_read(self):
         pair = self.tp(self.BytesIO(b"abcdef"), self.MockRawIO())
@@ -2146,7 +2146,7 @@ class TextIOWrapperTest(unittest.TestCase):
         if s:
             # The destructor *may* have printed an unraisable error, check it
             self.assertEqual(len(s.splitlines()), 1)
-            self.assertTrue(s.startswith("Exception IOError: "), s)
+            self.assertTrue(s.startswith("Exception OSError: "), s)
             self.assertTrue(s.endswith(" ignored"), s)
 
     # Systematic tests of the text I/O API
@@ -2218,7 +2218,7 @@ class TextIOWrapperTest(unittest.TestCase):
         f.seek(0)
         for line in f:
             self.assertEqual(line, "\xff\n")
-            self.assertRaises(IOError, f.tell)
+            self.assertRaises(OSError, f.tell)
         self.assertEqual(f.tell(), p2)
         f.close()
 
@@ -2322,7 +2322,7 @@ class TextIOWrapperTest(unittest.TestCase):
             def readable(self):
                 return False
         txt = self.TextIOWrapper(UnReadable())
-        self.assertRaises(IOError, txt.read)
+        self.assertRaises(OSError, txt.read)
 
     def test_read_one_by_one(self):
         txt = self.TextIOWrapper(self.BytesIO(b"AA\r\nBB"))
@@ -2497,9 +2497,9 @@ class TextIOWrapperTest(unittest.TestCase):
     def test_flush_error_on_close(self):
         txt = self.TextIOWrapper(self.BytesIO(self.testdata), encoding="ascii")
         def bad_flush():
-            raise IOError()
+            raise OSError()
         txt.flush = bad_flush
-        self.assertRaises(IOError, txt.close) # exception not swallowed
+        self.assertRaises(OSError, txt.close) # exception not swallowed
         self.assertTrue(txt.closed)
 
     def test_multi_close(self):
@@ -3032,7 +3032,7 @@ class SignalsTest(unittest.TestCase):
             # buffer, and block again.
             try:
                 wio.close()
-            except IOError as e:
+            except OSError as e:
                 if e.errno != errno.EBADF:
                     raise
 
@@ -3160,7 +3160,7 @@ class SignalsTest(unittest.TestCase):
             # buffer, and could block (in case of failure).
             try:
                 wio.close()
-            except IOError as e:
+            except OSError as e:
                 if e.errno != errno.EBADF:
                     raise
 
diff --git a/Lib/test/test_ioctl.py b/Lib/test/test_ioctl.py
index 531c9afbb5..7eb324ab57 100644
--- a/Lib/test/test_ioctl.py
+++ b/Lib/test/test_ioctl.py
@@ -8,7 +8,7 @@ get_attribute(termios, 'TIOCGPGRP') #Can't run tests without this feature
 
 try:
     tty = open("/dev/tty", "rb")
-except IOError:
+except OSError:
     raise unittest.SkipTest("Unable to open /dev/tty")
 else:
     # Skip if another process is in foreground
diff --git a/Lib/test/test_largefile.py b/Lib/test/test_largefile.py
index 1c6297ac7c..7502dc3c82 100644
--- a/Lib/test/test_largefile.py
+++ b/Lib/test/test_largefile.py
@@ -14,7 +14,7 @@ try:
     import signal
     # The default handler for SIGXFSZ is to abort the process.
     # By ignoring it, system calls exceeding the file size resource
-    # limit will raise IOError instead of crashing the interpreter.
+    # limit will raise OSError instead of crashing the interpreter.
     oldhandler = signal.signal(signal.SIGXFSZ, signal.SIG_IGN)
 except (ImportError, AttributeError):
     pass
@@ -162,7 +162,7 @@ def test_main():
             # flush, too!
             f.write(b'x')
             f.flush()
-        except (IOError, OverflowError):
+        except (OSError, OverflowError):
             f.close()
             unlink(TESTFN)
             raise unittest.SkipTest("filesystem does not have largefile support")
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index d8ce3159e4..c6cd64a5ba 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -3183,13 +3183,13 @@ class ShutdownTest(BaseTest):
         self.assertEqual('0 - release', self.called[-1])
 
     def test_with_ioerror_in_acquire(self):
-        self._test_with_failure_in_method('acquire', IOError)
+        self._test_with_failure_in_method('acquire', OSError)
 
     def test_with_ioerror_in_flush(self):
-        self._test_with_failure_in_method('flush', IOError)
+        self._test_with_failure_in_method('flush', OSError)
 
     def test_with_ioerror_in_close(self):
-        self._test_with_failure_in_method('close', IOError)
+        self._test_with_failure_in_method('close', OSError)
 
     def test_with_valueerror_in_acquire(self):
         self._test_with_failure_in_method('acquire', ValueError)
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index e5db94566f..9e1b7c761d 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -520,12 +520,12 @@ class TextIOTestMixin:
     def test_relative_seek(self):
         memio = self.ioclass()
 
-        self.assertRaises(IOError, memio.seek, -1, 1)
-        self.assertRaises(IOError, memio.seek, 3, 1)
-        self.assertRaises(IOError, memio.seek, -3, 1)
-        self.assertRaises(IOError, memio.seek, -1, 2)
-        self.assertRaises(IOError, memio.seek, 1, 1)
-        self.assertRaises(IOError, memio.seek, 1, 2)
+        self.assertRaises(OSError, memio.seek, -1, 1)
+        self.assertRaises(OSError, memio.seek, 3, 1)
+        self.assertRaises(OSError, memio.seek, -3, 1)
+        self.assertRaises(OSError, memio.seek, -1, 2)
+        self.assertRaises(OSError, memio.seek, 1, 1)
+        self.assertRaises(OSError, memio.seek, 1, 2)
 
     def test_textio_properties(self):
         memio = self.ioclass()
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
index e341bc73aa..3d883a9f20 100644
--- a/Lib/test/test_mmap.py
+++ b/Lib/test/test_mmap.py
@@ -684,11 +684,11 @@ class MmapTests(unittest.TestCase):
         self.assertTrue(m.closed)
 
     def test_context_manager_exception(self):
-        # Test that the IOError gets passed through
+        # Test that the OSError gets passed through
         with self.assertRaises(Exception) as exc:
             with mmap.mmap(-1, 10) as m:
-                raise IOError
-        self.assertIsInstance(exc.exception, IOError,
+                raise OSError
+        self.assertIsInstance(exc.exception, OSError,
                               "wrong exception raised in context manager")
         self.assertTrue(m.closed, "context manager failed")
 
@@ -709,7 +709,7 @@ class LargeMmapTests(unittest.TestCase):
             f.seek(num_zeroes)
             f.write(tail)
             f.flush()
-        except (IOError, OverflowError):
+        except (OSError, OverflowError):
             f.close()
             raise unittest.SkipTest("filesystem does not have largefile support")
         return f
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index 9c7a202d96..9ec0be2a70 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -2019,7 +2019,7 @@ class _TestManagerRestart(BaseTestCase):
             address=addr, authkey=authkey, serializer=SERIALIZER)
         try:
             manager.start()
-        except IOError as e:
+        except OSError as e:
             if e.errno != errno.EADDRINUSE:
                 raise
             # Retry after some time, in case the old socket was lingering
@@ -2132,9 +2132,9 @@ class _TestConnection(BaseTestCase):
             self.assertEqual(reader.writable, False)
             self.assertEqual(writer.readable, False)
             self.assertEqual(writer.writable, True)
-            self.assertRaises(IOError, reader.send, 2)
-            self.assertRaises(IOError, writer.recv)
-            self.assertRaises(IOError, writer.poll)
+            self.assertRaises(OSError, reader.send, 2)
+            self.assertRaises(OSError, writer.recv)
+            self.assertRaises(OSError, writer.poll)
 
     def test_spawn_close(self):
         # We test that a pipe connection can be closed by parent
@@ -2296,8 +2296,8 @@ class _TestConnection(BaseTestCase):
         if self.TYPE == 'processes':
             self.assertTrue(a.closed)
             self.assertTrue(b.closed)
-            self.assertRaises(IOError, a.recv)
-            self.assertRaises(IOError, b.recv)
+            self.assertRaises(OSError, a.recv)
+            self.assertRaises(OSError, b.recv)
 
 class _TestListener(BaseTestCase):
 
@@ -2318,7 +2318,7 @@ class _TestListener(BaseTestCase):
                     self.assertEqual(d.recv(), 1729)
 
         if self.TYPE == 'processes':
-            self.assertRaises(IOError, l.accept)
+            self.assertRaises(OSError, l.accept)
 
 class _TestListenerClient(BaseTestCase):
 
@@ -2866,12 +2866,12 @@ class TestInvalidHandle(unittest.TestCase):
     def test_invalid_handles(self):
         conn = multiprocessing.connection.Connection(44977608)
         try:
-            self.assertRaises((ValueError, IOError), conn.poll)
+            self.assertRaises((ValueError, OSError), conn.poll)
         finally:
             # Hack private attribute _handle to avoid printing an error
             # in conn.__del__
             conn._handle = None
-        self.assertRaises((ValueError, IOError),
+        self.assertRaises((ValueError, OSError),
                           multiprocessing.connection.Connection, -1)
 
 #
diff --git a/Lib/test/test_normalization.py b/Lib/test/test_normalization.py
index e3e2560356..db28e1aeb8 100644
--- a/Lib/test/test_normalization.py
+++ b/Lib/test/test_normalization.py
@@ -43,7 +43,7 @@ class NormalizationTest(unittest.TestCase):
         try:
             testdata = open_urlresource(TESTDATAURL, encoding="utf-8",
                                         check=check_version)
-        except (IOError, HTTPException):
+        except (OSError, HTTPException):
             self.skipTest("Could not retrieve " + TESTDATAURL)
         self.addCleanup(testdata.close)
         for line in testdata:
diff --git a/Lib/test/test_ossaudiodev.py b/Lib/test/test_ossaudiodev.py
index 3908a0506e..c9e2a24767 100644
--- a/Lib/test/test_ossaudiodev.py
+++ b/Lib/test/test_ossaudiodev.py
@@ -44,7 +44,7 @@ class OSSAudioDevTests(unittest.TestCase):
     def play_sound_file(self, data, rate, ssize, nchannels):
         try:
             dsp = ossaudiodev.open('w')
-        except IOError as msg:
+        except OSError as msg:
             if msg.args[0] in (errno.EACCES, errno.ENOENT,
                                errno.ENODEV, errno.EBUSY):
                 raise unittest.SkipTest(msg)
@@ -190,7 +190,7 @@ class OSSAudioDevTests(unittest.TestCase):
 def test_main():
     try:
         dsp = ossaudiodev.open('w')
-    except (ossaudiodev.error, IOError) as msg:
+    except (ossaudiodev.error, OSError) as msg:
         if msg.args[0] in (errno.EACCES, errno.ENOENT,
                            errno.ENODEV, errno.EBUSY):
             raise unittest.SkipTest(msg)
diff --git a/Lib/test/test_posix.py b/Lib/test/test_posix.py
index f4e8aba1b3..fba5078f09 100644
--- a/Lib/test/test_posix.py
+++ b/Lib/test/test_posix.py
@@ -550,7 +550,7 @@ class PosixTester(unittest.TestCase):
             self.assertEqual(st.st_flags | stat.UF_IMMUTABLE, new_st.st_flags)
             try:
                 fd = open(target_file, 'w+')
-            except IOError as e:
+            except OSError as e:
                 self.assertEqual(e.errno, errno.EPERM)
         finally:
             posix.chflags(target_file, st.st_flags)
diff --git a/Lib/test/test_resource.py b/Lib/test/test_resource.py
index 3c9b620702..0240c69834 100644
--- a/Lib/test/test_resource.py
+++ b/Lib/test/test_resource.py
@@ -61,7 +61,7 @@ class ResourceTest(unittest.TestCase):
                         for i in range(5):
                             time.sleep(.1)
                             f.flush()
-                    except IOError:
+                    except OSError:
                         if not limit_set:
                             raise
                     if limit_set:
diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py
index ad6228053b..f7b14b8c07 100644
--- a/Lib/test/test_shutil.py
+++ b/Lib/test/test_shutil.py
@@ -1515,7 +1515,7 @@ class TestCopyFile(unittest.TestCase):
             self._exited_with = exc_type, exc_val, exc_tb
             if self._raise_in_exit:
                 self._raised = True
-                raise IOError("Cannot close")
+                raise OSError("Cannot close")
             return self._suppress_at_exit
 
     def tearDown(self):
@@ -1529,12 +1529,12 @@ class TestCopyFile(unittest.TestCase):
     def test_w_source_open_fails(self):
         def _open(filename, mode='r'):
             if filename == 'srcfile':
-                raise IOError('Cannot open "srcfile"')
+                raise OSError('Cannot open "srcfile"')
             assert 0  # shouldn't reach here.
 
         self._set_shutil_open(_open)
 
-        self.assertRaises(IOError, shutil.copyfile, 'srcfile', 'destfile')
+        self.assertRaises(OSError, shutil.copyfile, 'srcfile', 'destfile')
 
     def test_w_dest_open_fails(self):
 
@@ -1544,14 +1544,14 @@ class TestCopyFile(unittest.TestCase):
             if filename == 'srcfile':
                 return srcfile
             if filename == 'destfile':
-                raise IOError('Cannot open "destfile"')
+                raise OSError('Cannot open "destfile"')
             assert 0  # shouldn't reach here.
 
         self._set_shutil_open(_open)
 
         shutil.copyfile('srcfile', 'destfile')
         self.assertTrue(srcfile._entered)
-        self.assertTrue(srcfile._exited_with[0] is IOError)
+        self.assertTrue(srcfile._exited_with[0] is OSError)
         self.assertEqual(srcfile._exited_with[1].args,
                          ('Cannot open "destfile"',))
 
@@ -1573,7 +1573,7 @@ class TestCopyFile(unittest.TestCase):
         self.assertTrue(srcfile._entered)
         self.assertTrue(destfile._entered)
         self.assertTrue(destfile._raised)
-        self.assertTrue(srcfile._exited_with[0] is IOError)
+        self.assertTrue(srcfile._exited_with[0] is OSError)
         self.assertEqual(srcfile._exited_with[1].args,
                          ('Cannot close',))
 
@@ -1591,7 +1591,7 @@ class TestCopyFile(unittest.TestCase):
 
         self._set_shutil_open(_open)
 
-        self.assertRaises(IOError,
+        self.assertRaises(OSError,
                           shutil.copyfile, 'srcfile', 'destfile')
         self.assertTrue(srcfile._entered)
         self.assertTrue(destfile._entered)
diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
index e475076dd9..1509a117d9 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -222,7 +222,7 @@ class DebuggingServerTests(unittest.TestCase):
             self.assertEqual(smtp.source_address, ('127.0.0.1', port))
             self.assertEqual(smtp.local_hostname, 'localhost')
             smtp.quit()
-        except IOError as e:
+        except OSError as e:
             if e.errno == errno.EADDRINUSE:
                 self.skipTest("couldn't bind to port %d" % port)
             raise
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index e5d9dbc1d8..be9206e99b 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -3723,7 +3723,7 @@ class FileObjectClassTestCase(SocketConnectedTest):
         # First read raises a timeout
         self.assertRaises(socket.timeout, self.read_file.read, 1)
         # Second read is disallowed
-        with self.assertRaises(IOError) as ctx:
+        with self.assertRaises(OSError) as ctx:
             self.read_file.read(1)
         self.assertIn("cannot read from timed out object", str(ctx.exception))
 
diff --git a/Lib/test/test_ssl.py b/Lib/test/test_ssl.py
index aa63ee6c6f..b3b878daca 100644
--- a/Lib/test/test_ssl.py
+++ b/Lib/test/test_ssl.py
@@ -246,15 +246,15 @@ class BasicSocketTests(unittest.TestCase):
         s = ssl.wrap_socket(sock, server_side=True, certfile=CERTFILE)
         self.assertRaisesRegex(ValueError, "can't connect in server-side mode",
                                 s.connect, (HOST, 8080))
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             with socket.socket() as sock:
                 ssl.wrap_socket(sock, certfile=WRONGCERT)
         self.assertEqual(cm.exception.errno, errno.ENOENT)
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             with socket.socket() as sock:
                 ssl.wrap_socket(sock, certfile=CERTFILE, keyfile=WRONGCERT)
         self.assertEqual(cm.exception.errno, errno.ENOENT)
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             with socket.socket() as sock:
                 ssl.wrap_socket(sock, certfile=WRONGCERT, keyfile=WRONGCERT)
         self.assertEqual(cm.exception.errno, errno.ENOENT)
@@ -442,7 +442,7 @@ class ContextTests(unittest.TestCase):
         ctx.load_cert_chain(CERTFILE)
         ctx.load_cert_chain(CERTFILE, keyfile=CERTFILE)
         self.assertRaises(TypeError, ctx.load_cert_chain, keyfile=CERTFILE)
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             ctx.load_cert_chain(WRONGCERT)
         self.assertEqual(cm.exception.errno, errno.ENOENT)
         with self.assertRaisesRegex(ssl.SSLError, "PEM lib"):
@@ -527,7 +527,7 @@ class ContextTests(unittest.TestCase):
         ctx.load_verify_locations(cafile=BYTES_CERTFILE, capath=None)
         self.assertRaises(TypeError, ctx.load_verify_locations)
         self.assertRaises(TypeError, ctx.load_verify_locations, None, None)
-        with self.assertRaises(IOError) as cm:
+        with self.assertRaises(OSError) as cm:
             ctx.load_verify_locations(WRONGCERT)
         self.assertEqual(cm.exception.errno, errno.ENOENT)
         with self.assertRaisesRegex(ssl.SSLError, "PEM lib"):
@@ -1229,11 +1229,11 @@ else:
             except OSError as x:
                 if support.verbose:
                     sys.stdout.write("\nOSError is %s\n" % x.args[1])
-            except IOError as x:
+            except OSError as x:
                 if x.errno != errno.ENOENT:
                     raise
                 if support.verbose:
-                    sys.stdout.write("\IOError is %s\n" % str(x))
+                    sys.stdout.write("\OSError is %s\n" % str(x))
             else:
                 raise AssertionError("Use of invalid cert should have failed!")
 
@@ -1387,7 +1387,7 @@ else:
                                        "badkey.pem"))
 
         def test_rude_shutdown(self):
-            """A brutal shutdown of an SSL server should raise an IOError
+            """A brutal shutdown of an SSL server should raise an OSError
             in the client when attempting handshake.
             """
             listener_ready = threading.Event()
@@ -1415,7 +1415,7 @@ else:
                     listener_gone.wait()
                     try:
                         ssl_sock = ssl.wrap_socket(c)
-                    except IOError:
+                    except OSError:
                         pass
                     else:
                         self.fail('connecting to closed SSL socket should have failed')
diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 22374d244d..eb97a2cc7a 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -489,7 +489,7 @@ class StructTest(unittest.TestCase):
     def test_bool(self):
         class ExplodingBool(object):
             def __bool__(self):
-                raise IOError
+                raise OSError
         for prefix in tuple("<>!=")+('',):
             false = (), [], [], '', 0
             true = [1], 'test', 5, -1, 0xffffffff+1, 0xffffffff/2
@@ -520,10 +520,10 @@ class StructTest(unittest.TestCase):
 
             try:
                 struct.pack(prefix + '?', ExplodingBool())
-            except IOError:
+            except OSError:
                 pass
             else:
-                self.fail("Expected IOError: struct.pack(%r, "
+                self.fail("Expected OSError: struct.pack(%r, "
                           "ExplodingBool())" % (prefix + '?'))
 
         for c in [b'\x01', b'\x7f', b'\xff', b'\x0f', b'\xf0']:
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 8bbf4aeebe..0c4328f172 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -1662,20 +1662,20 @@ class ContextManagerTest(unittest.TestCase):
         self.assertTrue(tar.closed, "context manager failed")
 
     def test_closed(self):
-        # The __enter__() method is supposed to raise IOError
+        # The __enter__() method is supposed to raise OSError
         # if the TarFile object is already closed.
         tar = tarfile.open(tarname)
         tar.close()
-        with self.assertRaises(IOError):
+        with self.assertRaises(OSError):
             with tar:
                 pass
 
     def test_exception(self):
-        # Test if the IOError exception is passed through properly.
+        # Test if the OSError exception is passed through properly.
         with self.assertRaises(Exception) as exc:
             with tarfile.open(tarname) as tar:
-                raise IOError
-        self.assertIsInstance(exc.exception, IOError,
+                raise OSError
+        self.assertIsInstance(exc.exception, OSError,
                               "wrong exception raised in context manager")
         self.assertTrue(tar.closed, "context manager failed")
 
@@ -1753,7 +1753,7 @@ class GzipMiscReadTest(MiscReadTest):
     def test_non_existent_targz_file(self):
         # Test for issue11513: prevent non-existent gzipped tarfiles raising
         # multiple exceptions.
-        with self.assertRaisesRegex(IOError, "xxx") as ex:
+        with self.assertRaisesRegex(OSError, "xxx") as ex:
             tarfile.open("xxx", self.mode)
         self.assertEqual(ex.exception.errno, errno.ENOENT)
 
diff --git a/Lib/test/test_timeout.py b/Lib/test/test_timeout.py
index c3c4acfb47..d28d62bf3a 100644
--- a/Lib/test/test_timeout.py
+++ b/Lib/test/test_timeout.py
@@ -194,7 +194,7 @@ class TCPTimeoutTestCase(TimeoutTestCase):
             sock.connect((whitehole))
         except socket.timeout:
             pass
-        except IOError as err:
+        except OSError as err:
             if err.errno == errno.ECONNREFUSED:
                 skip = False
         finally:
diff --git a/Lib/test/test_ucn.py b/Lib/test/test_ucn.py
index 68a3219560..319c213d54 100644
--- a/Lib/test/test_ucn.py
+++ b/Lib/test/test_ucn.py
@@ -172,7 +172,7 @@ class UnicodeNamesTest(unittest.TestCase):
         try:
             testdata = support.open_urlresource(url, encoding="utf-8",
                                                 check=check_version)
-        except (IOError, HTTPException):
+        except (OSError, HTTPException):
             self.skipTest("Could not retrieve " + url)
         self.addCleanup(testdata.close)
         for line in testdata:
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 1e30fa622c..72a0d8b728 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -232,7 +232,7 @@ class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin):
         self.check_read(b"1.1")
 
     def test_read_bogus(self):
-        # urlopen() should raise IOError for many error codes.
+        # urlopen() should raise OSError for many error codes.
         self.fakehttp(b'''HTTP/1.1 401 Authentication Required
 Date: Wed, 02 Jan 2008 03:03:54 GMT
 Server: Apache/1.3.33 (Debian GNU/Linux) mod_ssl/2.8.22 OpenSSL/0.9.7e
@@ -240,12 +240,12 @@ Connection: close
 Content-Type: text/html; charset=iso-8859-1
 ''')
         try:
-            self.assertRaises(IOError, urlopen, "http://python.org/")
+            self.assertRaises(OSError, urlopen, "http://python.org/")
         finally:
             self.unfakehttp()
 
     def test_invalid_redirect(self):
-        # urlopen() should raise IOError for many error codes.
+        # urlopen() should raise OSError for many error codes.
         self.fakehttp(b'''HTTP/1.1 302 Found
 Date: Wed, 02 Jan 2008 03:03:54 GMT
 Server: Apache/1.3.33 (Debian GNU/Linux) mod_ssl/2.8.22 OpenSSL/0.9.7e
@@ -260,11 +260,11 @@ Content-Type: text/html; charset=iso-8859-1
             self.unfakehttp()
 
     def test_empty_socket(self):
-        # urlopen() raises IOError if the underlying socket does not send any
+        # urlopen() raises OSError if the underlying socket does not send any
         # data. (#1680230)
         self.fakehttp(b'')
         try:
-            self.assertRaises(IOError, urlopen, "http://something")
+            self.assertRaises(OSError, urlopen, "http://something")
         finally:
             self.unfakehttp()
 
diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
index 6ef4200a4a..fb2413d83f 100644
--- a/Lib/test/test_urllib2_localnet.py
+++ b/Lib/test/test_urllib2_localnet.py
@@ -522,7 +522,7 @@ class TestUrlopen(unittest.TestCase):
     def test_bad_address(self):
         # Make sure proper exception is raised when connecting to a bogus
         # address.
-        self.assertRaises(IOError,
+        self.assertRaises(OSError,
                           # Given that both VeriSign and various ISPs have in
                           # the past or are presently hijacking various invalid
                           # domain name requests in an attempt to boost traffic
diff --git a/Lib/test/test_urllibnet.py b/Lib/test/test_urllibnet.py
index d3fe69dbce..e0782d2c51 100644
--- a/Lib/test/test_urllibnet.py
+++ b/Lib/test/test_urllibnet.py
@@ -121,7 +121,7 @@ class urlopenNetworkTests(unittest.TestCase):
         else:
             # This happens with some overzealous DNS providers such as OpenDNS
             self.skipTest("%r should not resolve for test to work" % bogus_domain)
-        self.assertRaises(IOError,
+        self.assertRaises(OSError,
                           # SF patch 809915:  In Sep 2003, VeriSign started
                           # highjacking invalid .com and .net addresses to
                           # boost traffic to their own site.  This test
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index ac6983f135..369cb4feb1 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -929,7 +929,7 @@ class OtherTests(unittest.TestCase):
         try:
             with zipfile.ZipFile(TESTFN, 'a') as zf:
                 zf.writestr(filename, content)
-        except IOError:
+        except OSError:
             self.fail('Could not append data to a non-existent zip file.')
 
         self.assertTrue(os.path.exists(TESTFN))
@@ -995,7 +995,7 @@ class OtherTests(unittest.TestCase):
         chk = zipfile.is_zipfile(fp)
         self.assertTrue(chk)
 
-    def test_non_existent_file_raises_IOError(self):
+    def test_non_existent_file_raises_OSError(self):
         # make sure we don't raise an AttributeError when a partially-constructed
         # ZipFile instance is finalized; this tests for regression on SF tracker
         # bug #403871.
@@ -1007,7 +1007,7 @@ class OtherTests(unittest.TestCase):
         # it is ignored, but the user should be sufficiently annoyed by
         # the message on the output that regression will be noticed
         # quickly.
-        self.assertRaises(IOError, zipfile.ZipFile, TESTFN)
+        self.assertRaises(OSError, zipfile.ZipFile, TESTFN)
 
     def test_empty_file_raises_BadZipFile(self):
         f = open(TESTFN, 'w')
@@ -1281,7 +1281,7 @@ class OtherTests(unittest.TestCase):
     def test_open_empty_file(self):
         # Issue 1710703: Check that opening a file with less than 22 bytes
         # raises a BadZipFile exception (rather than the previously unhelpful
-        # IOError)
+        # OSError)
         f = open(TESTFN, 'w')
         f.close()
         self.assertRaises(zipfile.BadZipFile, zipfile.ZipFile, TESTFN, 'r')
diff --git a/Lib/test/test_zipimport.py b/Lib/test/test_zipimport.py
index f7cb8b977f..9c3f6d43c6 100644
--- a/Lib/test/test_zipimport.py
+++ b/Lib/test/test_zipimport.py
@@ -459,7 +459,7 @@ class BadFileZipImportTestCase(unittest.TestCase):
 
             self.assertRaises(error, z.load_module, 'abc')
             self.assertRaises(error, z.get_code, 'abc')
-            self.assertRaises(IOError, z.get_data, 'abc')
+            self.assertRaises(OSError, z.get_data, 'abc')
             self.assertRaises(error, z.get_source, 'abc')
             self.assertRaises(error, z.is_package, 'abc')
         finally:
diff --git a/Lib/token.py b/Lib/token.py
index 31fae0a078..7470c8c376 100755
--- a/Lib/token.py
+++ b/Lib/token.py
@@ -93,7 +93,7 @@ def _main():
         outFileName = args[1]
     try:
         fp = open(inFileName)
-    except IOError as err:
+    except OSError as err:
         sys.stdout.write("I/O error: %s\n" % str(err))
         sys.exit(1)
     lines = fp.read().split("\n")
@@ -112,7 +112,7 @@ def _main():
     # load the output skeleton from the target:
     try:
         fp = open(outFileName)
-    except IOError as err:
+    except OSError as err:
         sys.stderr.write("I/O error: %s\n" % str(err))
         sys.exit(2)
     format = fp.read().split("\n")
@@ -129,7 +129,7 @@ def _main():
     format[start:end] = lines
     try:
         fp = open(outFileName, 'w')
-    except IOError as err:
+    except OSError as err:
         sys.stderr.write("I/O error: %s\n" % str(err))
         sys.exit(4)
     fp.write("\n".join(format))
diff --git a/Lib/tokenize.py b/Lib/tokenize.py
index cbf91ef222..2fbde0fa9b 100644
--- a/Lib/tokenize.py
+++ b/Lib/tokenize.py
@@ -670,7 +670,7 @@ def main():
         error(err.args[0], filename, (line, column))
     except SyntaxError as err:
         error(err, filename)
-    except IOError as err:
+    except OSError as err:
         error(err)
     except KeyboardInterrupt:
         print("interrupted\n")
diff --git a/Lib/trace.py b/Lib/trace.py
index 317b5fd6c8..7eb35ebcb0 100644
--- a/Lib/trace.py
+++ b/Lib/trace.py
@@ -237,7 +237,7 @@ class CoverageResults:
                 counts, calledfuncs, callers = \
                         pickle.load(open(self.infile, 'rb'))
                 self.update(self.__class__(counts, calledfuncs, callers))
-            except (IOError, EOFError, ValueError) as err:
+            except (OSError, EOFError, ValueError) as err:
                 print(("Skipping counts file %r: %s"
                                       % (self.infile, err)), file=sys.stderr)
 
@@ -347,7 +347,7 @@ class CoverageResults:
             try:
                 pickle.dump((self.counts, self.calledfuncs, self.callers),
                             open(self.outfile, 'wb'), 1)
-            except IOError as err:
+            except OSError as err:
                 print("Can't save counts files because %s" % err, file=sys.stderr)
 
     def write_results_file(self, path, lines, lnotab, lines_hit, encoding=None):
@@ -355,7 +355,7 @@ class CoverageResults:
 
         try:
             outfile = open(path, "w", encoding=encoding)
-        except IOError as err:
+        except OSError as err:
             print(("trace: Could not open %r for writing: %s"
                                   "- skipping" % (path, err)), file=sys.stderr)
             return 0, 0
@@ -436,7 +436,7 @@ def _find_executable_linenos(filename):
         with tokenize.open(filename) as f:
             prog = f.read()
             encoding = f.encoding
-    except IOError as err:
+    except OSError as err:
         print(("Not printing coverage data for %r: %s"
                               % (filename, err)), file=sys.stderr)
         return {}
@@ -801,7 +801,7 @@ def main(argv=None):
                 '__cached__': None,
             }
             t.runctx(code, globs, globs)
-        except IOError as err:
+        except OSError as err:
             _err_exit("Cannot run file %r because: %s" % (sys.argv[0], err))
         except SystemExit:
             pass
diff --git a/Lib/urllib/error.py b/Lib/urllib/error.py
index 237ed6b9bb..45b7169793 100644
--- a/Lib/urllib/error.py
+++ b/Lib/urllib/error.py
@@ -1,6 +1,6 @@
 """Exception classes raised by urllib.
 
-The base exception class is URLError, which inherits from IOError.  It
+The base exception class is URLError, which inherits from OSError.  It
 doesn't define any behavior of its own, but is the base class for all
 exceptions defined in this package.
 
@@ -17,11 +17,11 @@ __all__ = ['URLError', 'HTTPError', 'ContentTooShortError']
 
 
 # do these error classes make sense?
-# make sure all of the IOError stuff is overridden.  we just want to be
+# make sure all of the OSError stuff is overridden.  we just want to be
 # subtypes.
 
-class URLError(IOError):
-    # URLError is a sub-type of IOError, but it doesn't share any of
+class URLError(OSError):
+    # URLError is a sub-type of OSError, but it doesn't share any of
     # the implementation.  need to override __init__ and __str__.
     # It sets self.args for compatibility with other EnvironmentError
     # subclasses, but args doesn't have the typical format with errno in
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index 2ebd89260f..8035f7c554 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -18,7 +18,7 @@ urlopen(url, data=None) -- Basic usage is the same as original
 urllib.  pass the url and optionally data to post to an HTTP URL, and
 get a file-like object back.  One difference is that you can also pass
 a Request instance instead of URL.  Raises a URLError (subclass of
-IOError); for HTTP errors, raises an HTTPError, which can also be
+OSError); for HTTP errors, raises an HTTPError, which can also be
 treated as a valid response.
 
 build_opener -- Function that creates a new OpenerDirector instance.
@@ -1722,17 +1722,17 @@ class URLopener:
         except (HTTPError, URLError):
             raise
         except OSError as msg:
-            raise IOError('socket error', msg).with_traceback(sys.exc_info()[2])
+            raise OSError('socket error', msg).with_traceback(sys.exc_info()[2])
 
     def open_unknown(self, fullurl, data=None):
         """Overridable interface to open unknown URL type."""
         type, url = splittype(fullurl)
-        raise IOError('url error', 'unknown url type', type)
+        raise OSError('url error', 'unknown url type', type)
 
     def open_unknown_proxy(self, proxy, fullurl, data=None):
         """Overridable interface to open unknown URL type."""
         type, url = splittype(fullurl)
-        raise IOError('url error', 'invalid proxy for %s' % type, proxy)
+        raise OSError('url error', 'invalid proxy for %s' % type, proxy)
 
     # External interface
     def retrieve(self, url, filename=None, reporthook=None, data=None):
@@ -1748,7 +1748,7 @@ class URLopener:
                 hdrs = fp.info()
                 fp.close()
                 return url2pathname(splithost(url1)[1]), hdrs
-            except IOError as msg:
+            except OSError as msg:
                 pass
         fp = self.open(url, data)
         try:
@@ -1841,7 +1841,7 @@ class URLopener:
                 if proxy_bypass(realhost):
                     host = realhost
 
-        if not host: raise IOError('http error', 'no host given')
+        if not host: raise OSError('http error', 'no host given')
 
         if proxy_passwd:
             proxy_passwd = unquote(proxy_passwd)
@@ -1914,7 +1914,7 @@ class URLopener:
         return self.http_error_default(url, fp, errcode, errmsg, headers)
 
     def http_error_default(self, url, fp, errcode, errmsg, headers):
-        """Default error handler: close the connection and raise IOError."""
+        """Default error handler: close the connection and raise OSError."""
         fp.close()
         raise HTTPError(url, errcode, errmsg, headers, None)
 
@@ -2041,7 +2041,7 @@ class URLopener:
         try:
             [type, data] = url.split(',', 1)
         except ValueError:
-            raise IOError('data error', 'bad data URL')
+            raise OSError('data error', 'bad data URL')
         if not type:
             type = 'text/plain;charset=US-ASCII'
         semi = type.rfind(';')
diff --git a/Lib/uuid.py b/Lib/uuid.py
index 0df0743c4c..5d091b992f 100644
--- a/Lib/uuid.py
+++ b/Lib/uuid.py
@@ -329,7 +329,7 @@ def _find_mac(command, args, hw_identifiers, get_index):
                         if words[i] in hw_identifiers:
                             return int(
                                 words[get_index(i)].replace(':', ''), 16)
-        except IOError:
+        except OSError:
             continue
     return None
 
@@ -371,7 +371,7 @@ def _ipconfig_getnode():
     for dir in dirs:
         try:
             pipe = os.popen(os.path.join(dir, 'ipconfig') + ' /all')
-        except IOError:
+        except OSError:
             continue
         else:
             for line in pipe:
diff --git a/Lib/warnings.py b/Lib/warnings.py
index edbbb5eda4..b05a08ee83 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -16,7 +16,7 @@ def showwarning(message, category, filename, lineno, file=None, line=None):
         file = sys.stderr
     try:
         file.write(formatwarning(message, category, filename, lineno, line))
-    except IOError:
+    except OSError:
         pass # the file (probably stderr) is invalid - this warning gets lost.
 
 def formatwarning(message, category, filename, lineno, line=None):
diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index f1a071b779..a59639bad9 100644
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -422,7 +422,7 @@ class Grail(BaseBrowser):
                 # no good; attempt to clean it out, but don't fail:
                 try:
                     os.unlink(fn)
-                except IOError:
+                except OSError:
                     pass
             else:
                 return s
diff --git a/Lib/xml/etree/ElementInclude.py b/Lib/xml/etree/ElementInclude.py
index 6cc1b44e95..73e491e5d9 100644
--- a/Lib/xml/etree/ElementInclude.py
+++ b/Lib/xml/etree/ElementInclude.py
@@ -71,8 +71,8 @@ class FatalIncludeError(SyntaxError):
 # @return The expanded resource.  If the parse mode is "xml", this
 #    is an ElementTree instance.  If the parse mode is "text", this
 #    is a Unicode string.  If the loader fails, it can return None
-#    or raise an IOError exception.
-# @throws IOError If the loader fails to load the resource.
+#    or raise an OSError exception.
+# @throws OSError If the loader fails to load the resource.
 
 def default_loader(href, parse, encoding=None):
     if parse == "xml":
@@ -95,7 +95,7 @@ def default_loader(href, parse, encoding=None):
 #     that implements the same interface as <b>default_loader</b>.
 # @throws FatalIncludeError If the function fails to include a given
 #     resource, or if the tree contains malformed XInclude elements.
-# @throws IOError If the function fails to load a given resource.
+# @throws OSError If the function fails to load a given resource.
 
 def include(elem, loader=None):
     if loader is None:
diff --git a/Lib/xmlrpc/client.py b/Lib/xmlrpc/client.py
index a2e8e337a7..ff422652e6 100644
--- a/Lib/xmlrpc/client.py
+++ b/Lib/xmlrpc/client.py
@@ -1045,7 +1045,7 @@ def gzip_decode(data):
     gzf = gzip.GzipFile(mode="rb", fileobj=f)
     try:
         decoded = gzf.read()
-    except IOError:
+    except OSError:
         raise ValueError("invalid data")
     f.close()
     gzf.close()
@@ -1386,7 +1386,7 @@ class ServerProxy:
         # get the url
         type, uri = urllib.parse.splittype(uri)
         if type not in ("http", "https"):
-            raise IOError("unsupported XML-RPC protocol")
+            raise OSError("unsupported XML-RPC protocol")
         self.__host, self.__handler = urllib.parse.splithost(uri)
         if not self.__handler:
             self.__handler = "/RPC2"
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index df4ed91207..a2791cd30e 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -164,7 +164,7 @@ def _check_zipfile(fp):
     try:
         if _EndRecData(fp):
             return True         # file has correct magic number
-    except IOError:
+    except OSError:
         pass
     return False
 
@@ -180,7 +180,7 @@ def is_zipfile(filename):
         else:
             with open(filename, "rb") as fp:
                 result = _check_zipfile(fp)
-    except IOError:
+    except OSError:
         pass
     return result
 
@@ -190,7 +190,7 @@ def _EndRecData64(fpin, offset, endrec):
     """
     try:
         fpin.seek(offset - sizeEndCentDir64Locator, 2)
-    except IOError:
+    except OSError:
         # If the seek fails, the file is not large enough to contain a ZIP64
         # end-of-archive record, so just return the end record we were given.
         return endrec
@@ -238,7 +238,7 @@ def _EndRecData(fpin):
     # file if this is the case).
     try:
         fpin.seek(-sizeEndCentDir, 2)
-    except IOError:
+    except OSError:
         return None
     data = fpin.read()
     if data[0:4] == stringEndArchive and data[-2:] == b"\000\000":
@@ -895,7 +895,7 @@ class ZipFile:
             modeDict = {'r' : 'rb', 'w': 'wb', 'a' : 'r+b'}
             try:
                 self.fp = io.open(file, modeDict[mode])
-            except IOError:
+            except OSError:
                 if mode == 'a':
                     mode = key = 'w'
                     self.fp = io.open(file, modeDict[mode])
@@ -946,7 +946,7 @@ class ZipFile:
         fp = self.fp
         try:
             endrec = _EndRecData(fp)
-        except IOError:
+        except OSError:
             raise BadZipFile("File is not a zip file")
         if not endrec:
             raise BadZipFile("File is not a zip file")
diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 20b7acb886..b940417823 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -2066,7 +2066,6 @@ Name(identifier id, expr_context_ty ctx, int lineno, int col_offset, PyArena
      *arena)
 {
         expr_ty p;
-        assert(PyUnicode_CompareWithASCIIString(id, "True") && PyUnicode_CompareWithASCIIString(id, "False") && PyUnicode_CompareWithASCIIString(id, "None"));
         if (!id) {
                 PyErr_SetString(PyExc_ValueError,
                                 "field id is required for Name");
diff --git a/Python/importlib.h b/Python/importlib.h
index 269d498e52..0d5705053b 100644
--- a/Python/importlib.h
+++ b/Python/importlib.h
@@ -2131,7 +2131,7 @@ unsigned char _Py_M__importlib[] = {
     117,8,0,0,0,116,111,107,101,110,105,122,101,117,12,0,
     0,0,103,101,116,95,102,105,108,101,110,97,109,101,117,8,
     0,0,0,103,101,116,95,100,97,116,97,117,7,0,0,0,
-    73,79,69,114,114,111,114,117,11,0,0,0,73,109,112,111,
+    79,83,69,114,114,111,114,117,11,0,0,0,73,109,112,111,
     114,116,69,114,114,111,114,117,3,0,0,0,95,105,111,117,
     7,0,0,0,66,121,116,101,115,73,79,117,8,0,0,0,
     114,101,97,100,108,105,110,101,117,15,0,0,0,100,101,116,
@@ -2244,7 +2244,7 @@ unsigned char _Py_M__importlib[] = {
     111,116,73,109,112,108,101,109,101,110,116,101,100,69,114,114,
     111,114,117,10,0,0,0,112,97,116,104,95,115,116,97,116,
     115,117,3,0,0,0,105,110,116,117,8,0,0,0,103,101,
-    116,95,100,97,116,97,117,7,0,0,0,73,79,69,114,114,
+    116,95,100,97,116,97,117,7,0,0,0,79,83,69,114,114,
     111,114,117,20,0,0,0,95,98,121,116,101,115,95,102,114,
     111,109,95,98,121,116,101,99,111,100,101,117,11,0,0,0,
     73,109,112,111,114,116,69,114,114,111,114,117,8,0,0,0,