Issue #23016: A warning no longer produces AttributeError when the program

is run with pythonw.exe.

1 files changed, 3 insertions, 0 deletions

diff --git a/Lib/warnings.py b/Lib/warnings.py
index 5d5c9a9dcb..3a8fc5db65 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -11,6 +11,9 @@ def showwarning(message, category, filename, lineno, file=None, line=None):
     """Hook to write a warning to a file; replace if you like."""
     if file is None:
         file = sys.stderr
+        if file is None:
+            # sys.stderr is None when ran with pythonw.exe - warnings get lost
+            return
     try:
         file.write(formatwarning(message, category, filename, lineno, line))
     except OSError: