all: merge branch 'danw/gerror-bgo762868'

https://bugzilla.gnome.org/show_bug.cgi?id=762868

47 files changed, 174 insertions, 195 deletions

diff --git a/callouts/nm-dispatcher.c b/callouts/nm-dispatcher.c
index de13bd0de3..7ddffb0493 100644
--- a/callouts/nm-dispatcher.c
+++ b/callouts/nm-dispatcher.c
@@ -549,8 +549,7 @@ script_dispatch (ScriptInfo *script)
 			request->num_scripts_nowait++;
 		return TRUE;
 	} else {
-		_LOG_S_W (script, "complete: failed to execute script: %s (%d)",
-		          error->message, error->code);
+		_LOG_S_W (script, "complete: failed to execute script: %s", error->message);
 		script->result = DISPATCH_RESULT_EXEC_FAILED;
 		script->error = g_strdup (error->message);
 		request->num_scripts_done++;
@@ -594,8 +593,8 @@ find_scripts (const char *str_action)
 		dirname = NMD_SCRIPT_DIR_DEFAULT;
 
 	if (!(dir = g_dir_open (dirname, 0, &error))) {
-		g_message ("find-scripts: Failed to open dispatcher directory '%s': (%d) %s",
-		           dirname, error->code, error->message);
+		g_message ("find-scripts: Failed to open dispatcher directory '%s': %s",
+		           dirname, error->message);
 		g_error_free (error);
 		return NULL;
 	}
diff --git a/clients/cli/connections.c b/clients/cli/connections.c
index d263154d22..4cb85f7287 100644
--- a/clients/cli/connections.c
+++ b/clients/cli/connections.c
@@ -2302,7 +2302,7 @@ nmc_activate_connection (NmCli *nmc,
 		/* Virtual connection may not have their interfaces created yet */
 		if (!device_found && !nm_connection_is_virtual (connection)) {
 			g_set_error (error, NMCLI_ERROR, NMC_RESULT_ERROR_CON_ACTIVATION,
-				     "%s", local && local->message ? local->message : _("unknown error"));
+			             "%s", local->message);
 			g_clear_error (&local);
 			return FALSE;
 		}
@@ -2450,8 +2450,8 @@ do_connection_up (NmCli *nmc, int argc, char **argv)
 
 	if (!nmc_activate_connection (nmc, connection, ifname, ap, nsp, pwds, activate_connection_cb, &error)) {
 		g_string_printf (nmc->return_text, _("Error: %s."),
-		                 error ? error->message : _("unknown error"));
-		nmc->return_value = error ? error->code : NMC_RESULT_ERROR_CON_ACTIVATION;
+		                 error->message);
+		nmc->return_value = error->code;
 		g_clear_error (&error);
 		nmc->should_wait--;
 		goto error;
@@ -7898,7 +7898,7 @@ load_history_cmds (const char *uuid)
 	filename = g_build_filename (g_get_home_dir (), NMCLI_EDITOR_HISTORY, NULL);
 	kf = g_key_file_new ();
 	if (!g_key_file_load_from_file (kf, filename, G_KEY_FILE_KEEP_COMMENTS, &err)) {
-		if (err->code == G_KEY_FILE_ERROR_PARSE)
+		if (g_error_matches (err, G_KEY_FILE_ERROR, G_KEY_FILE_ERROR_PARSE))
 			g_print ("Warning: %s parse error: %s\n", filename, err->message);
 		g_key_file_free (kf);
 		g_free (filename);
@@ -7933,8 +7933,8 @@ save_history_cmds (const char *uuid)
 		filename = g_build_filename (g_get_home_dir (), NMCLI_EDITOR_HISTORY, NULL);
 		kf = g_key_file_new ();
 		if (!g_key_file_load_from_file (kf, filename, G_KEY_FILE_KEEP_COMMENTS, &err)) {
-			if (   err->code != G_FILE_ERROR_NOENT
-			    && err->code != G_KEY_FILE_ERROR_NOT_FOUND) {
+			if (   !g_error_matches (err, G_FILE_ERROR, G_FILE_ERROR_NOENT)
+			    && !g_error_matches (err, G_KEY_FILE_ERROR, G_KEY_FILE_ERROR_NOT_FOUND)) {
 				g_print ("Warning: %s parse error: %s\n", filename, err->message);
 				g_key_file_free (kf);
 				g_free (filename);
@@ -10724,7 +10724,7 @@ do_connection_export (NmCli *nmc, int argc, char **argv)
 
 	if (!nm_vpn_editor_plugin_export (plugin, path, connection, &error)) {
 		g_string_printf (nmc->return_text, _("Error: failed to export '%s': %s."),
-		                 nm_connection_get_id (connection), error ? error->message : "(unknown)");
+		                 nm_connection_get_id (connection), error->message);
 		nmc->return_value = NMC_RESULT_ERROR_UNKNOWN;
 		goto finish;
 	}
diff --git a/libnm-core/nm-setting-8021x.c b/libnm-core/nm-setting-8021x.c
index 0ecb988af2..cc8ea66ed7 100644
--- a/libnm-core/nm-setting-8021x.c
+++ b/libnm-core/nm-setting-8021x.c
@@ -2907,8 +2907,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->ca_cert);
 		priv->ca_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_CA_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2929,8 +2928,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->client_cert);
 		priv->client_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_CLIENT_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2959,8 +2957,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->phase2_ca_cert);
 		priv->phase2_ca_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_CA_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2981,8 +2978,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->phase2_client_cert);
 		priv->phase2_client_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_CLIENT_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
@@ -3006,8 +3002,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->private_key);
 		priv->private_key = set_cert_prop_helper (value, NM_SETTING_802_1X_PRIVATE_KEY, &error);
 		if (error) {
-			g_warning ("Error setting private key (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting private key (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
@@ -3023,8 +3018,7 @@ set_property (GObject *object, guint prop_id,
 			g_bytes_unref (priv->phase2_private_key);
 		priv->phase2_private_key = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_PRIVATE_KEY, &error);
 		if (error) {
-			g_warning ("Error setting private key (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting private key (invalid data): %s", error->message);
 			g_error_free (error);
 		}
 		break;
diff --git a/libnm-glib/nm-active-connection.c b/libnm-glib/nm-active-connection.c
index db6e7ab732..aa79e1ac04 100644
--- a/libnm-glib/nm-active-connection.c
+++ b/libnm-glib/nm-active-connection.c
@@ -139,8 +139,8 @@ _nm_active_connection_type_for_path (DBusGConnection *connection,
 		else
 			type = NM_TYPE_ACTIVE_CONNECTION;
 	} else {
-		g_warning ("Error in getting active connection 'Vpn' property: (%d) %s",
-		           error->code, error->message);
+		g_warning ("Error in getting active connection 'Vpn' property: %s",
+		           error->message);
 		g_error_free (error);
 		type = G_TYPE_INVALID;
 	}
diff --git a/libnm-glib/nm-client.c b/libnm-glib/nm-client.c
index fc105e53e7..13d02943f4 100644
--- a/libnm-glib/nm-client.c
+++ b/libnm-glib/nm-client.c
@@ -513,7 +513,7 @@ activate_info_complete (ActivateInfo *info,
 		                  error,
 		                  info->user_data);
 	} else if (error)
-		g_warning ("Device activation failed: (%d) %s", error->code, error->message);
+		g_warning ("Device activation failed: %s", error->message);
 
 	priv->pending_activations = g_slist_remove (priv->pending_activations, info);
 }
@@ -812,8 +812,8 @@ nm_client_deactivate_connection (NMClient *client, NMActiveConnection *active)
 	                        DBUS_TYPE_G_OBJECT_PATH, path,
 	                        G_TYPE_INVALID,
 	                        G_TYPE_INVALID)) {
-		g_warning ("Could not deactivate connection '%s': %s", 
-		           path, error ? error->message : "(unknown)");
+		g_warning ("Could not deactivate connection '%s': %s",
+		           path, NM_G_ERROR_MSG (error));
 		g_clear_error (&error);
 	}
 }
@@ -1839,8 +1839,8 @@ constructed (GObject *object)
 	GError *error = NULL;
 
 	if (!nm_utils_init (&error)) {
-		g_warning ("Couldn't initilize nm-utils/crypto system: %d %s",
-		           error->code, error->message);
+		g_warning ("Couldn't initilize nm-utils/crypto system: %s",
+		           error->message);
 		g_clear_error (&error);
 	}
 
diff --git a/libnm-glib/nm-device.c b/libnm-glib/nm-device.c
index 312f970059..3392d230d3 100644
--- a/libnm-glib/nm-device.c
+++ b/libnm-glib/nm-device.c
@@ -2198,12 +2198,11 @@ device_operation_cb (DBusGProxy *proxy,
 	if (info->fn)
 		info->fn (info->device, error, info->user_data);
 	else if (error) {
-		g_warning ("%s: device %s %s failed: (%d) %s",
+		g_warning ("%s: device %s %s failed: %s",
 		           __func__,
 		           nm_object_get_path (NM_OBJECT (info->device)),
 		           info->method,
-		           error ? error->code : -1,
-		           error && error->message ? error->message : "(unknown)");
+		           NM_G_ERROR_MSG (error));
 	}
 	g_clear_error (&error);
 
diff --git a/libnm-glib/nm-object.c b/libnm-glib/nm-object.c
index b252dc7a6d..c7201cda26 100644
--- a/libnm-glib/nm-object.c
+++ b/libnm-glib/nm-object.c
@@ -1402,11 +1402,10 @@ _nm_object_reload_property (NMObject *object,
 	                                     G_TYPE_INVALID,
 	                                     G_TYPE_VALUE, &value,
 	                                     G_TYPE_INVALID)) {
-		dbgmsg ("%s: Error getting '%s' for %s: (%d) %s\n",
+		dbgmsg ("%s: Error getting '%s' for %s: %s\n",
 		        __func__,
 		        prop_name,
 		        nm_object_get_path (object),
-		        err->code,
 		        err->message);
 		g_clear_error (&err);
 		return;
diff --git a/libnm-glib/nm-remote-connection.c b/libnm-glib/nm-remote-connection.c
index 2031b27f11..132032f488 100644
--- a/libnm-glib/nm-remote-connection.c
+++ b/libnm-glib/nm-remote-connection.c
@@ -454,11 +454,10 @@ replace_settings (NMRemoteConnection *self, GHashTable *new_settings)
 	if (nm_connection_replace_settings (NM_CONNECTION (self), new_settings, &error))
 		g_signal_emit (self, signals[UPDATED], 0, new_settings);
 	else {
-		g_warning ("%s: error updating connection %s settings: (%d) %s",
+		g_warning ("%s: error updating connection %s settings: %s",
 		           __func__,
 		           nm_connection_get_path (NM_CONNECTION (self)),
-		           error ? error->code : -1,
-		           (error && error->message) ? error->message : "(unknown)");
+		           error->message);
 		g_clear_error (&error);
 
 		g_signal_emit (self, signals[REMOVED], 0);
diff --git a/libnm-glib/nm-remote-settings.c b/libnm-glib/nm-remote-settings.c
index fa2b325f05..b64743a99c 100644
--- a/libnm-glib/nm-remote-settings.c
+++ b/libnm-glib/nm-remote-settings.c
@@ -503,7 +503,7 @@ connection_inited (GObject *source, GAsyncResult *result, gpointer user_data)
 		if (!dbus_g_error_has_name (error, "org.freedesktop.NetworkManager.Settings.PermissionDenied"))
 			g_hash_table_remove (priv->pending, path);
 
-		if (print_once && error->code == DBUS_GERROR_LIMITS_EXCEEDED) {
+		if (print_once && g_error_matches (error, DBUS_GERROR, DBUS_GERROR_LIMITS_EXCEEDED)) {
 			g_printerr ("Warning: libnm-glib:%s(): a D-Bus limit exceeded: %s. The application might not work properly.\n"
 			            "Consider increasing max_replies_per_connection limit in /etc/dbus-1/system.d/org.freedesktop.NetworkManager.conf "
 			            "like <limit name=\"max_replies_per_connection\">2048</limit>",
@@ -574,9 +574,8 @@ fetch_connections_done (DBusGProxy *proxy,
 		if (   !g_error_matches (error, DBUS_GERROR, DBUS_GERROR_SERVICE_UNKNOWN)
 		    && !g_error_matches (error, DBUS_GERROR, DBUS_GERROR_NAME_HAS_NO_OWNER)
 		    && priv->service_running) {
-			g_warning ("%s: error fetching connections: (%d) %s.",
+			g_warning ("%s: error fetching connections: %s.",
 			           __func__,
-			           error->code,
 			           error->message ? error->message : "(unknown)");
 		}
 		g_clear_error (&error);
diff --git a/libnm-glib/nm-secret-agent.c b/libnm-glib/nm-secret-agent.c
index a0966f9f6c..0a86245568 100644
--- a/libnm-glib/nm-secret-agent.c
+++ b/libnm-glib/nm-secret-agent.c
@@ -330,9 +330,8 @@ verify_request (NMSecretAgent *self,
 		g_set_error (error,
 		             NM_SECRET_AGENT_ERROR,
 		             NM_SECRET_AGENT_ERROR_INVALID_CONNECTION,
-		             "Invalid connection: (%d) %s",
-		             local ? local->code : -1,
-		             (local && local->message) ? local->message : "(unknown)");
+		             "Invalid connection: %s",
+		             local->message);
 		g_clear_error (&local);
 	}
 
diff --git a/libnm-glib/nm-vpn-plugin.c b/libnm-glib/nm-vpn-plugin.c
index 9f941fcb60..d117e53092 100644
--- a/libnm-glib/nm-vpn-plugin.c
+++ b/libnm-glib/nm-vpn-plugin.c
@@ -455,8 +455,7 @@ _connect_generic (NMVPNPlugin *plugin,
 	connection = nm_connection_new_from_hash (properties, &local);
 	if (!connection) {
 		g_set_error (error, NM_VPN_PLUGIN_ERROR, NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		             "Invalid connection: (%d) %s",
-		             local->code, local->message);
+		             "Invalid connection: %s", local->message);
 		g_clear_error (&local);
 		return FALSE;
 	}
@@ -537,9 +536,9 @@ impl_vpn_plugin_need_secrets (NMVPNPlugin *plugin,
 		g_set_error (err,
 		             NM_VPN_PLUGIN_ERROR,
 		             NM_VPN_PLUGIN_ERROR_CONNECTION_INVALID,
-		             "The connection was invalid: '%s' / '%s' invalid: %d.",
+		             "The connection was invalid: '%s' / '%s' invalid.",
 		             g_type_name (nm_connection_lookup_setting_type_by_quark (cnfh_err->domain)),
-		             cnfh_err->message, cnfh_err->code);
+		             cnfh_err->message);
 		g_error_free (cnfh_err);
 		return FALSE;
 	}
@@ -595,8 +594,8 @@ impl_vpn_plugin_new_secrets (NMVPNPlugin *plugin,
 	connection = nm_connection_new_from_hash (properties, &local);
 	if (!connection) {
 		g_set_error (error, NM_VPN_PLUGIN_ERROR, NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		             "Invalid connection: (%d) %s",
-		             local->code, local->message);
+		             "Invalid connection: %s",
+		             local->message);
 		g_clear_error (&local);
 		return FALSE;
 	}
diff --git a/libnm-util/nm-setting-8021x.c b/libnm-util/nm-setting-8021x.c
index f476b2489b..4f974a413a 100644
--- a/libnm-util/nm-setting-8021x.c
+++ b/libnm-util/nm-setting-8021x.c
@@ -2878,8 +2878,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->ca_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_CA_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2902,8 +2902,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->client_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_CLIENT_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2934,8 +2934,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->phase2_ca_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_CA_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2958,8 +2958,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->phase2_client_cert = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_CLIENT_CERT, &error);
 		if (error) {
-			g_warning ("Error setting certificate (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting certificate (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -2985,8 +2985,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->private_key = set_cert_prop_helper (value, NM_SETTING_802_1X_PRIVATE_KEY, &error);
 		if (error) {
-			g_warning ("Error setting private key (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting private key (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -3004,8 +3004,8 @@ set_property (GObject *object, guint prop_id,
 		}
 		priv->phase2_private_key = set_cert_prop_helper (value, NM_SETTING_802_1X_PHASE2_PRIVATE_KEY, &error);
 		if (error) {
-			g_warning ("Error setting private key (invalid data): (%d) %s",
-			           error->code, error->message);
+			g_warning ("Error setting private key (invalid data): %s",
+			           error->message);
 			g_error_free (error);
 		}
 		break;
@@ -3726,8 +3726,8 @@ nm_setting_802_1x_class_init (NMSetting8021xClass *setting_class)
 
 	/* Initialize crypto lbrary. */
 	if (!nm_utils_init (&error)) {
-		g_warning ("Couldn't initilize nm-utils/crypto system: %d %s",
-		           error->code, error->message);
+		g_warning ("Couldn't initilize nm-utils/crypto system: %s",
+		           error->message);
 		g_error_free (error);
 	}
 }
diff --git a/libnm-util/nm-utils.c b/libnm-util/nm-utils.c
index 7c9def1da2..24f233f913 100644
--- a/libnm-util/nm-utils.c
+++ b/libnm-util/nm-utils.c
@@ -1514,18 +1514,14 @@ nm_utils_uuid_generate_from_string (const char *s)
 	g_return_val_if_fail (s && *s, NULL);
 
 	if (!nm_utils_init (&error)) {
-		g_warning ("error initializing crypto: (%d) %s",
-		           error ? error->code : 0,
-		           error ? error->message : "unknown");
+		g_warning ("error initializing crypto: %s", error->message);
 		if (error)
 			g_error_free (error);
 		return NULL;
 	}
 
 	if (!crypto_md5_hash (NULL, 0, s, strlen (s), (char *) uuid, sizeof (uuid), &error)) {
-		g_warning ("error generating UUID: (%d) %s",
-		           error ? error->code : 0,
-		           error ? error->message : "unknown");
+		g_warning ("error generating UUID: %s", error->message);
 		if (error)
 			g_error_free (error);
 		return NULL;
diff --git a/libnm/nm-object.c b/libnm/nm-object.c
index b35f6822a5..9a5dcd6f0d 100644
--- a/libnm/nm-object.c
+++ b/libnm/nm-object.c
@@ -1280,11 +1280,10 @@ _nm_object_reload_property (NMObject *object,
 	                                G_DBUS_CALL_FLAGS_NONE, 15000,
 	                                NULL, &err);
 	if (!ret) {
-		dbgmsg ("%s: Error getting '%s' for %s: (%d) %s\n",
+		dbgmsg ("%s: Error getting '%s' for %s: %s\n",
 		        __func__,
 		        prop_name,
 		        nm_object_get_path (object),
-		        err->code,
 		        err->message);
 		g_clear_error (&err);
 		return;
diff --git a/libnm/nm-remote-connection.c b/libnm/nm-remote-connection.c
index d2b55bd84f..c4a0b6aeb0 100644
--- a/libnm/nm-remote-connection.c
+++ b/libnm/nm-remote-connection.c
@@ -564,11 +564,10 @@ replace_settings (NMRemoteConnection *self, GVariant *new_settings)
 	GError *error = NULL;
 
 	if (!nm_connection_replace_settings (NM_CONNECTION (self), new_settings, &error)) {
-		g_warning ("%s: error updating connection %s settings: (%d) %s",
+		g_warning ("%s: error updating connection %s settings: %s",
 		           __func__,
 		           nm_connection_get_path (NM_CONNECTION (self)),
-		           error ? error->code : -1,
-		           (error && error->message) ? error->message : "(unknown)");
+		           error->message);
 		g_clear_error (&error);
 	}
 }
diff --git a/libnm/nm-vpn-plugin-old.c b/libnm/nm-vpn-plugin-old.c
index 19f14176fa..74861edc46 100644
--- a/libnm/nm-vpn-plugin-old.c
+++ b/libnm/nm-vpn-plugin-old.c
@@ -470,8 +470,8 @@ _connect_generic (NMVpnPluginOld *plugin,
 		g_dbus_method_invocation_return_error (context,
 		                                       NM_VPN_PLUGIN_ERROR,
 		                                       NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		                                       "Invalid connection: (%d) %s",
-		                                       error->code, error->message);
+		                                       "Invalid connection: %s",
+		                                       error->message);
 		g_clear_error (&error);
 	}
 
@@ -611,8 +611,8 @@ impl_vpn_plugin_old_new_secrets (NMVpnPluginOld *plugin,
 		g_dbus_method_invocation_return_error (context,
 		                                       NM_VPN_PLUGIN_ERROR,
 		                                       NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		                                       "Invalid connection: (%d) %s",
-		                                       error->code, error->message);
+		                                       "Invalid connection: %s",
+		                                       error->message);
 		g_clear_error (&error);
 		return;
 	}
diff --git a/libnm/nm-vpn-service-plugin.c b/libnm/nm-vpn-service-plugin.c
index 5fbd359025..876d479817 100644
--- a/libnm/nm-vpn-service-plugin.c
+++ b/libnm/nm-vpn-service-plugin.c
@@ -486,8 +486,8 @@ _connect_generic (NMVpnServicePlugin *plugin,
 		g_dbus_method_invocation_return_error (context,
 		                                       NM_VPN_PLUGIN_ERROR,
 		                                       NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		                                       "Invalid connection: (%d) %s",
-		                                       error->code, error->message);
+		                                       "Invalid connection: %s",
+		                                       error->message);
 		g_clear_error (&error);
 		return;
 	}
@@ -631,8 +631,8 @@ impl_vpn_service_plugin_new_secrets (NMVpnServicePlugin *plugin,
 		g_dbus_method_invocation_return_error (context,
 		                                       NM_VPN_PLUGIN_ERROR,
 		                                       NM_VPN_PLUGIN_ERROR_BAD_ARGUMENTS,
-		                                       "Invalid connection: (%d) %s",
-		                                       error->code, error->message);
+		                                       "Invalid connection: %s",
+		                                       error->message);
 		g_clear_error (&error);
 		return;
 	}
diff --git a/shared/nm-macros-internal.h b/shared/nm-macros-internal.h
index aa38bacf55..dafce87795 100644
--- a/shared/nm-macros-internal.h
+++ b/shared/nm-macros-internal.h
@@ -116,6 +116,26 @@ GS_DEFINE_CLEANUP_FUNCTION(void*, _nm_auto_free_impl, free)
 
 /********************************************************/
 
+/**
+ * NM_G_ERROR_MSG:
+ * @error: (allow none): the #GError instance
+ *
+ * All functions must follow the convention that when they
+ * return a failure, they must also set the GError to a valid
+ * message. For external API however, we want to be extra
+ * careful before accessing the error instance. Use NM_G_ERROR_MSG()
+ * which is safe to use on NULL.
+ *
+ * Returns: the error message.
+ **/
+static inline const char *
+NM_G_ERROR_MSG (GError *error)
+{
+	return error ? (error->message ? : "(null)") : "(no-error)"; \
+}
+
+/********************************************************/
+
 /* macro to return strlen() of a compile time string. */
 #define NM_STRLEN(str)     ( sizeof ("" str) - 1 )
 
diff --git a/shared/nm-test-utils.h b/shared/nm-test-utils.h
index 542081b891..4b1c5d2436 100644
--- a/shared/nm-test-utils.h
+++ b/shared/nm-test-utils.h
@@ -154,7 +154,7 @@ inline static void
 _nmtst_assert_success (gboolean success, GError *error, const char *file, int line)
 {
 	if (!success || error)
-		g_error ("(%s:%d) FAILURE success=%d, error=%s", file, line, success, error && error->message ? error->message : "(no error)");
+		g_error ("(%s:%d) FAILURE success=%d, error=%s", file, line, success, error ? error->message : "(no error)");
 }
 #define nmtst_assert_success(success, error) _nmtst_assert_success ((success), (error), __FILE__, __LINE__)
 
diff --git a/src/devices/bluetooth/nm-bluez-device.c b/src/devices/bluetooth/nm-bluez-device.c
index 71226813de..a009746d02 100644
--- a/src/devices/bluetooth/nm-bluez-device.c
+++ b/src/devices/bluetooth/nm-bluez-device.c
@@ -246,9 +246,8 @@ pan_connection_check_create (NMBluezDevice *self)
 		priv->pan_connection = added;
 		nm_log_dbg (LOGD_BT, "bluez[%s] added new Bluetooth connection for NAP device: '%s' (%s)", priv->path, id, uuid);
 	} else {
-		nm_log_warn (LOGD_BT, "bluez[%s] couldn't add new Bluetooth connection for NAP device: '%s' (%s): %d / %s",
-		             priv->path, id, uuid, error ? error->code : -1,
-		             (error && error->message) ? error->message : "(unknown)");
+		nm_log_warn (LOGD_BT, "bluez[%s] couldn't add new Bluetooth connection for NAP device: '%s' (%s): %s",
+		             priv->path, id, uuid, error->message);
 		g_clear_error (&error);
 
 	}
diff --git a/src/devices/bluetooth/nm-bluez5-manager.c b/src/devices/bluetooth/nm-bluez5-manager.c
index e44e87d8a9..8fcfaedf5b 100644
--- a/src/devices/bluetooth/nm-bluez5-manager.c
+++ b/src/devices/bluetooth/nm-bluez5-manager.c
@@ -231,8 +231,7 @@ on_proxy_acquired (GObject *object,
 	priv->proxy = g_dbus_proxy_new_for_bus_finish (res, &error);
 
 	if (!priv->proxy) {
-		nm_log_warn (LOGD_BT, "Couldn't acquire object manager proxy: %s",
-		             error && error->message ? error->message : "(unknown)");
+		nm_log_warn (LOGD_BT, "Couldn't acquire object manager proxy: %s", error->message);
 		g_clear_error (&error);
 		return;
 	}
diff --git a/src/devices/bluetooth/nm-device-bt.c b/src/devices/bluetooth/nm-device-bt.c
index e151b79559..4ecb56edbc 100644
--- a/src/devices/bluetooth/nm-device-bt.c
+++ b/src/devices/bluetooth/nm-device-bt.c
@@ -497,8 +497,8 @@ modem_ip4_config_result (NMModem *modem,
 
 	if (error) {
 		_LOGW (LOGD_MB | LOGD_IP4 | LOGD_BT,
-		       "retrieving IP4 configuration failed: (%d) %s",
-		       error->code, error->message ? error->message : "(unknown)");
+		       "retrieving IP4 configuration failed: %s",
+		       error->message);
 
 		nm_device_state_changed (device, NM_DEVICE_STATE_FAILED, NM_DEVICE_STATE_REASON_IP_CONFIG_UNAVAILABLE);
 	} else
@@ -728,8 +728,7 @@ bluez_connect_cb (GObject *object,
 	                                         res, &error);
 
 	if (!device) {
-		_LOGW (LOGD_BT, "Error connecting with bluez: %s",
-		       error && error->message ? error->message : "(unknown)");
+		_LOGW (LOGD_BT, "Error connecting with bluez: %s", error->message);
 		g_clear_error (&error);
 
 		nm_device_state_changed (NM_DEVICE (self),
diff --git a/src/devices/nm-device-ethernet.c b/src/devices/nm-device-ethernet.c
index 84f10abf4b..37b48b3a11 100644
--- a/src/devices/nm-device-ethernet.c
+++ b/src/devices/nm-device-ethernet.c
@@ -177,7 +177,7 @@ _update_s390_subchannels (NMDeviceEthernet *self)
 	dir = g_dir_open (parent_path, 0, &error);
 	if (!dir) {
 		_LOGW (LOGD_DEVICE | LOGD_HW, "failed to open directory '%s': %s",
-		       parent_path, error && error->message ? error->message : "(unknown)");
+		       parent_path, error->message);
 		g_clear_error (&error);
 		goto out;
 	}
@@ -597,13 +597,13 @@ supplicant_iface_state_cb (NMSupplicantInterface *iface,
 			if (!success) {
 				_LOGE (LOGD_DEVICE | LOGD_ETHER,
 				       "Activation: (ethernet) couldn't send security configuration to the supplicant: %s",
-				       error ? error->message : "<BUG>");
+				       error->message);
 				g_clear_error (&error);
 			}
 		} else {
 			_LOGE (LOGD_DEVICE | LOGD_ETHER,
 			       "Activation: (ethernet) couldn't build security configuration: %s",
-			       error ? error->message : "<BUG>");
+			       error->message);
 			g_clear_error (&error);
 		}
 
diff --git a/src/devices/nm-device-factory.c b/src/devices/nm-device-factory.c
index bd0ec002ec..5ce4333f58 100644
--- a/src/devices/nm-device-factory.c
+++ b/src/devices/nm-device-factory.c
@@ -355,7 +355,7 @@ read_device_factory_paths (void)
 	if (!dir) {
 		nm_log_warn (LOGD_HW, "device plugin: failed to open directory %s: %s",
 		             NMPLUGINDIR,
-		             (error && error->message) ? error->message : "(unknown)");
+		             error->message);
 		g_clear_error (&error);
 		return NULL;
 	}
@@ -499,7 +499,7 @@ nm_device_factory_manager_load_factories (NMDeviceFactoryManagerFactoryFunc call
 		factory = create_func (&error);
 		if (!factory) {
 			nm_log_warn (LOGD_HW, "(%s): failed to initialize device factory: %s",
-			             item, error ? error->message : "unknown");
+			             item, NM_G_ERROR_MSG (error));
 			g_clear_error (&error);
 			g_module_close (plugin);
 			continue;
diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index cdd3f7cb1a..0897b27e55 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -2883,7 +2883,7 @@ nm_device_generate_connection (NMDevice *self, NMDevice *master)
 		                                               &error))
 		{
 			_LOGE (LOGD_DEVICE, "master device '%s' failed to update slave connection: %s",
-			       nm_device_get_iface (master), error ? error->message : "(unknown error)");
+			       nm_device_get_iface (master), error->message);
 			g_error_free (error);
 			g_object_unref (connection);
 			return NULL;
@@ -6631,7 +6631,7 @@ start_sharing (NMDevice *self, NMIP4Config *config)
 
 	if (!nm_dnsmasq_manager_start (priv->dnsmasq_manager, config, &error)) {
 		_LOGE (LOGD_SHARING, "share: (%s) failed to start dnsmasq: %s",
-		       ip_iface, (error && error->message) ? error->message : "(unknown)");
+		       ip_iface, error->message);
 		g_error_free (error);
 		nm_act_request_set_shared (req, FALSE);
 		return FALSE;
diff --git a/src/devices/wifi/nm-device-wifi.c b/src/devices/wifi/nm-device-wifi.c
index da2a0f4a89..2bf3b56a16 100644
--- a/src/devices/wifi/nm-device-wifi.c
+++ b/src/devices/wifi/nm-device-wifi.c
@@ -2491,7 +2491,7 @@ act_stage2_config (NMDevice *device, NMDeviceStateReason *reason)
 	if (config == NULL) {
 		_LOGE (LOGD_DEVICE | LOGD_WIFI,
 		       "Activation: (wifi) couldn't build wireless configuration: %s",
-		       error ? error->message : "<BUG>");
+		       error->message);
 		g_clear_error (&error);
 		*reason = NM_DEVICE_STATE_REASON_SUPPLICANT_CONFIG_FAILED;
 		goto out;
@@ -2506,7 +2506,7 @@ act_stage2_config (NMDevice *device, NMDeviceStateReason *reason)
 	if (!nm_supplicant_interface_set_config (priv->sup_iface, config, &error)) {
 		_LOGE (LOGD_DEVICE | LOGD_WIFI,
 		       "Activation: (wifi) couldn't send wireless configuration to the supplicant: %s",
-		       error ? error->message : "<BUG>");
+		       error->message);
 		g_clear_error (&error);
 		*reason = NM_DEVICE_STATE_REASON_SUPPLICANT_CONFIG_FAILED;
 		goto out;
diff --git a/src/devices/wifi/tests/test-wifi-ap-utils.c b/src/devices/wifi/tests/test-wifi-ap-utils.c
index 01990beed7..838368c479 100644
--- a/src/devices/wifi/tests/test-wifi-ap-utils.c
+++ b/src/devices/wifi/tests/test-wifi-ap-utils.c
@@ -37,7 +37,7 @@
 	if (expected) { \
 		if (!success) { \
 			g_assert (error != NULL); \
-			g_warning ("Failed to complete connection: (%d) %s", error->code, error->message); \
+			g_warning ("Failed to complete connection: %s", error->message); \
 		} \
 		g_assert (success == TRUE); \
 		g_assert (error == NULL); \
diff --git a/src/devices/wwan/nm-device-modem.c b/src/devices/wwan/nm-device-modem.c
index e9c4f02e20..a8361c4976 100644
--- a/src/devices/wwan/nm-device-modem.c
+++ b/src/devices/wwan/nm-device-modem.c
@@ -157,8 +157,8 @@ modem_ip4_config_result (NMModem *modem,
 	g_return_if_fail (nm_device_activate_ip4_state_in_conf (device) == TRUE);
 
 	if (error) {
-		_LOGW (LOGD_MB | LOGD_IP4, "retrieving IPv4 configuration failed: (%d) %s",
-		       error->code, error->message ? error->message : "(unknown)");
+		_LOGW (LOGD_MB | LOGD_IP4, "retrieving IPv4 configuration failed: %s",
+		       error->message);
 
 		nm_device_state_changed (device, NM_DEVICE_STATE_FAILED, NM_DEVICE_STATE_REASON_IP_CONFIG_UNAVAILABLE);
 	} else {
@@ -184,8 +184,7 @@ modem_ip6_config_result (NMModem *modem,
 	g_return_if_fail (nm_device_activate_ip6_state_in_conf (device) == TRUE);
 
 	if (error) {
-		_LOGW (LOGD_MB | LOGD_IP6, "retrieving IPv6 configuration failed: (%d) %s",
-		       error->code, error->message ? error->message : "(unknown)");
+		_LOGW (LOGD_MB | LOGD_IP6, "retrieving IPv6 configuration failed: %s", error->message);
 
 		nm_device_state_changed (device, NM_DEVICE_STATE_FAILED, NM_DEVICE_STATE_REASON_IP_CONFIG_UNAVAILABLE);
 		return;
diff --git a/src/devices/wwan/nm-modem-broadband.c b/src/devices/wwan/nm-modem-broadband.c
index 6343416cbd..363a878af1 100644
--- a/src/devices/wwan/nm-modem-broadband.c
+++ b/src/devices/wwan/nm-modem-broadband.c
@@ -464,7 +464,7 @@ connect_context_step (NMModemBroadband *self)
 			nm_log_warn (LOGD_MB, "(%s): Failed to connect '%s': %s",
 			             nm_modem_get_uid (NM_MODEM (self)),
 			             nm_connection_get_id (ctx->connection),
-			             error ? error->message : "unknown error");
+			             error->message);
 			g_clear_error (&error);
 
 			g_signal_emit_by_name (self, NM_MODEM_PREPARE_RESULT, FALSE, NM_DEVICE_STATE_REASON_MODEM_INIT_FAILED);
@@ -734,7 +734,7 @@ set_power_state_low_ready (MMModem *modem,
 		/* Log but ignore errors; not all modems support low power state */
 		nm_log_dbg (LOGD_MB, "(%s): failed to set modem low power state: %s",
 		            nm_modem_get_uid (NM_MODEM (self)),
-		            error && error->message ? error->message : "(unknown)");
+		            NM_G_ERROR_MSG (error));
 		g_clear_error (&error);
 	}
 
@@ -759,7 +759,7 @@ modem_disable_ready (MMModem *modem_iface,
 	} else {
 		nm_log_warn (LOGD_MB, "(%s): failed to disable modem: %s",
 		             nm_modem_get_uid (NM_MODEM (self)),
-		             error && error->message ? error->message : "(unknown)");
+		             NM_G_ERROR_MSG (error));
 		nm_modem_set_prev_state (NM_MODEM (self), "disable failed");
 		g_clear_error (&error);
 	}
@@ -778,7 +778,7 @@ modem_enable_ready (MMModem *modem_iface,
 	if (!mm_modem_enable_finish (modem_iface, res, &error)) {
 		nm_log_warn (LOGD_MB, "(%s) failed to enable modem: %s",
 		             nm_modem_get_uid (NM_MODEM (self)),
-		             error && error->message ? error->message : "(unknown)");
+		             NM_G_ERROR_MSG (error));
 		nm_modem_set_prev_state (NM_MODEM (self), "enable failed");
 		g_clear_error (&error);
 	}
@@ -1259,7 +1259,7 @@ get_sim_ready (MMModem *modem,
 	} else {
 		nm_log_warn (LOGD_MB, "(%s): failed to retrieve SIM object: %s",
 		             nm_modem_get_uid (NM_MODEM (self)),
-		             error && error->message ? error->message : "(unknown)");
+		             NM_G_ERROR_MSG (error));
 	}
 	g_clear_error (&error);
 	g_object_unref (self);
diff --git a/src/devices/wwan/nm-modem-manager.c b/src/devices/wwan/nm-modem-manager.c
index 79082c410c..e26321b0a4 100644
--- a/src/devices/wwan/nm-modem-manager.c
+++ b/src/devices/wwan/nm-modem-manager.c
@@ -145,7 +145,7 @@ modem_object_added (MMManager *modem_manager,
 		handle_new_modem (self, modem);
 	else {
 		nm_log_warn (LOGD_MB, "failed to create modem: %s",
-		             error ? error->message : "(unknown)");
+		             error->message);
 	}
 	g_clear_error (&error);
 }
diff --git a/src/devices/wwan/nm-modem.c b/src/devices/wwan/nm-modem.c
index c1736ecf84..2a8a9d1e92 100644
--- a/src/devices/wwan/nm-modem.c
+++ b/src/devices/wwan/nm-modem.c
@@ -545,10 +545,9 @@ ppp_stage3_ip_config_start (NMModem *self,
 
 		ret = NM_ACT_STAGE_RETURN_POSTPONE;
 	} else {
-		nm_log_err (LOGD_PPP, "(%s): error starting PPP: (%d) %s",
+		nm_log_err (LOGD_PPP, "(%s): error starting PPP: %s",
 		            nm_modem_get_uid (self),
-		            error ? error->code : -1,
-		            error && error->message ? error->message : "(unknown)");
+		            error->message);
 		g_error_free (error);
 
 		nm_exported_object_clear_and_unexport (&priv->ppp_manager);
diff --git a/src/dhcp-manager/nm-dhcp-dhclient.c b/src/dhcp-manager/nm-dhcp-dhclient.c
index bc4345fe6c..e5329ef33c 100644
--- a/src/dhcp-manager/nm-dhcp-dhclient.c
+++ b/src/dhcp-manager/nm-dhcp-dhclient.c
@@ -362,9 +362,9 @@ dhclient_start (NMDhcpClient *client,
 			priv->lease_file = g_strdup (g_file_get_path (dst));
 		} else {
 			/* Failure; just use the existing leasefile */
-			nm_log_warn (log_domain, "Failed to copy leasefile %s to %s: (%d) %s",
+			nm_log_warn (log_domain, "Failed to copy leasefile %s to %s: %s",
 			             g_file_get_path (src), g_file_get_path (dst),
-			             error->code, error->message);
+			             error->message);
 			g_clear_error (&error);
 		}
 		g_object_unref (src);
@@ -378,10 +378,9 @@ dhclient_start (NMDhcpClient *client,
 		success = nm_dhcp_dhclient_save_duid (priv->lease_file, escaped, &error);
 		g_free (escaped);
 		if (!success) {
-			nm_log_warn (log_domain, "(%s): failed to save DUID to %s: (%d) %s.",
+			nm_log_warn (log_domain, "(%s): failed to save DUID to %s: %s.",
 			             iface, priv->lease_file,
-			             error ? error->code : -1,
-			             error && error->message ? error->message : "(unknown)");
+			             error->message);
 			g_free (pid_file);
 			return FALSE;
 		}
@@ -577,8 +576,8 @@ get_duid (NMDhcpClient *client)
 		duid = nm_dhcp_dhclient_read_duid (leasefile, &error);
 
 		if (error) {
-			nm_log_warn (LOGD_DHCP, "Failed to read leasefile '%s': (%d) %s",
-			             leasefile, error->code, error->message);
+			nm_log_warn (LOGD_DHCP, "Failed to read leasefile '%s': %s",
+			             leasefile, error->message);
 			g_clear_error (&error);
 		}
 		g_free (leasefile);
@@ -589,10 +588,9 @@ get_duid (NMDhcpClient *client)
 		nm_log_dbg (LOGD_DHCP, "Looking for default DHCPv6 DUID in '%s'.", priv->def_leasefile);
 		duid = nm_dhcp_dhclient_read_duid (priv->def_leasefile, &error);
 		if (error) {
-			nm_log_warn (LOGD_DHCP, "Failed to read leasefile '%s': (%d) %s",
+			nm_log_warn (LOGD_DHCP, "Failed to read leasefile '%s': %s",
 			             priv->def_leasefile,
-			             error ? error->code : -1,
-			             error ? error->message : "(unknown)");
+			             error->message);
 			g_clear_error (&error);
 		}
 	}
diff --git a/src/dns-manager/nm-dns-dnsmasq.c b/src/dns-manager/nm-dns-dnsmasq.c
index 8663dfd81c..919fa67608 100644
--- a/src/dns-manager/nm-dns-dnsmasq.c
+++ b/src/dns-manager/nm-dns-dnsmasq.c
@@ -283,10 +283,9 @@ update (NMDnsPlugin *plugin,
 
 	/* Write out the config file */
 	if (!g_file_set_contents (CONFFILE, conf->str, -1, &error)) {
-		nm_log_warn (LOGD_DNS, "Failed to write dnsmasq config file %s: (%d) %s",
+		nm_log_warn (LOGD_DNS, "Failed to write dnsmasq config file %s: %s",
 		             CONFFILE,
-		             error ? error->code : -1,
-		             error && error->message ? error->message : "(unknown)");
+		             error->message);
 		g_clear_error (&error);
 		goto out;
 	}
diff --git a/src/dns-manager/nm-dns-plugin.c b/src/dns-manager/nm-dns-plugin.c
index 8313ed13cd..6bdcbce168 100644
--- a/src/dns-manager/nm-dns-plugin.c
+++ b/src/dns-manager/nm-dns-plugin.c
@@ -175,9 +175,8 @@ nm_dns_plugin_child_spawn (NMDnsPlugin *self,
 		nm_log_dbg (LOGD_DNS, "%s started with pid %d", priv->progname, priv->pid);
 		priv->watch_id = g_child_watch_add (priv->pid, (GChildWatchFunc) watch_cb, self);
 	} else {
-		nm_log_warn (LOGD_DNS, "Failed to spawn %s: (%d) %s",
-		             priv->progname, error ? error->code : -1,
-		             error && error->message ? error->message : "(unknown)");
+		nm_log_warn (LOGD_DNS, "Failed to spawn %s: %s",
+		             priv->progname, error->message);
 		g_clear_error (&error);
 	}
 
diff --git a/src/main.c b/src/main.c
index 9495a9eff1..0f074b012d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -216,8 +216,7 @@ print_config (NMConfigCmdLineOptions *config_cli)
 
 	config = nm_config_new (config_cli, NULL, &error);
 	if (config == NULL) {
-		fprintf (stderr, _("Failed to read configuration: %s\n"),
-		         (error && error->message) ? error->message : _("unknown"));
+		fprintf (stderr, _("Failed to read configuration: %s\n"), error->message);
 		return 7;
 	}
 
@@ -359,9 +358,8 @@ main (int argc, char *argv[])
 	nm_config_cmd_line_options_free (config_cli);
 	config_cli = NULL;
 	if (config == NULL) {
-		fprintf (stderr, _("Failed to read configuration: (%d) %s\n"),
-		         error ? error->code : -1,
-		         (error && error->message) ? error->message : _("unknown"));
+		fprintf (stderr, _("Failed to read configuration: %s\n"),
+		         error->message);
 		exit (1);
 	}
 
@@ -413,10 +411,9 @@ main (int argc, char *argv[])
 
 	/* Parse the state file */
 	if (!parse_state_file (global_opt.state_file, &net_enabled, &wifi_enabled, &wwan_enabled, &error)) {
-		nm_log_err (LOGD_CORE, "State file %s parsing failed: (%d) %s",
+		nm_log_err (LOGD_CORE, "State file %s parsing failed: %s",
 		            global_opt.state_file,
-		            error ? error->code : -1,
-		            (error && error->message) ? error->message : _("unknown"));
+		            error->message);
 		/* Not a hard failure */
 	}
 	g_clear_error (&error);
diff --git a/src/nm-activation-request.c b/src/nm-activation-request.c
index 17b1d75dca..acc3e4ca76 100644
--- a/src/nm-activation-request.c
+++ b/src/nm-activation-request.c
@@ -303,9 +303,8 @@ nm_act_request_set_shared (NMActRequest *req, gboolean shared)
 			nm_log_info (LOGD_SHARING, "Executing: %s", cmd);
 			if (!g_spawn_sync ("/", argv, envp, G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL,
 			                   NULL, NULL, NULL, NULL, &status, &error)) {
-				nm_log_warn (LOGD_SHARING, "Error executing command: (%d) %s",
-				             error ? error->code : -1,
-				             (error && error->message) ? error->message : "(unknown)");
+				nm_log_warn (LOGD_SHARING, "Error executing command: %s",
+				             error->message);
 				g_clear_error (&error);
 			} else if (WEXITSTATUS (status)) {
 				nm_log_warn (LOGD_SHARING, "** Command returned exit status %d.",
diff --git a/src/nm-auth-utils.c b/src/nm-auth-utils.c
index e741546bbc..928e88b0c4 100644
--- a/src/nm-auth-utils.c
+++ b/src/nm-auth-utils.c
@@ -335,8 +335,8 @@ pk_call_cb (GObject *object, GAsyncResult *result, gpointer user_data)
 	}
 
 	if (error) {
-		nm_log_warn (LOGD_CORE, "error requesting auth for %s: (%d) %s",
-		             call->permission, error->code, error->message);
+		nm_log_warn (LOGD_CORE, "error requesting auth for %s: %s",
+		             call->permission, error->message);
 
 		if (!call->chain->error) {
 			call->chain->error = error;
diff --git a/src/nm-manager.c b/src/nm-manager.c
index a99d77fffb..e7eb7c63c8 100644
--- a/src/nm-manager.c
+++ b/src/nm-manager.c
@@ -1627,7 +1627,7 @@ get_existing_connection (NMManager *self, NMDevice *device, gboolean *out_genera
 		_LOGW (LOGD_SETTINGS, "(%s) Couldn't save generated connection '%s': %s",
 		       nm_device_get_iface (device),
 		       nm_connection_get_id (connection),
-		       (error && error->message) ? error->message : "(unknown)");
+		       error->message);
 		g_clear_error (&error);
 	}
 	g_object_unref (connection);
@@ -1658,10 +1658,9 @@ assume_connection (NMManager *self, NMDevice *device, NMSettingsConnection *conn
 	g_object_unref (subject);
 
 	if (!active) {
-		_LOGW (LOGD_DEVICE, "assumed connection %s failed to activate: (%d) %s",
+		_LOGW (LOGD_DEVICE, "assumed connection %s failed to activate: %s",
 		       nm_connection_get_path (NM_CONNECTION (connection)),
-		       error ? error->code : -1,
-		       error && error->message ? error->message : "(unknown)");
+		       error->message);
 		g_error_free (error);
 		return FALSE;
 	}
@@ -3671,7 +3670,6 @@ deactivate_net_auth_done_cb (NMAuthChain *chain,
 
 	path = nm_auth_chain_get_data (chain, "path");
 	result = nm_auth_chain_get_result (chain, NM_AUTH_PERMISSION_NETWORK_CONTROL);
-	active = active_connection_get_by_path (self, path);
 
 	if (auth_error) {
 		_LOGD (LOGD_CORE, "Disconnect request failed: %s", auth_error->message);
@@ -3689,9 +3687,10 @@ deactivate_net_auth_done_cb (NMAuthChain *chain,
 		                                       path,
 		                                       NM_DEVICE_STATE_REASON_USER_REQUESTED,
 		                                       &error))
-			g_assert (error);
+			nm_assert (error);
 	}
 
+	active = active_connection_get_by_path (self, path);
 	if (active) {
 		nm_audit_log_connection_op (NM_AUDIT_OP_CONN_DEACTIVATE,
 		                            nm_active_connection_get_settings_connection (active),
@@ -4009,10 +4008,9 @@ _internal_enable (NMManager *self, gboolean enable)
 		                                G_TYPE_BOOLEAN, (gpointer) &enable,
 		                                &err)) {
 			/* Not a hard error */
-			_LOGW (LOGD_SUSPEND, "writing to state file %s failed: (%d) %s.",
+			_LOGW (LOGD_SUSPEND, "writing to state file %s failed: %s",
 			       priv->state_file,
-			       err ? err->code : -1,
-			       (err && err->message) ? err->message : "unknown");
+			       err->message);
 		}
 	}
 
@@ -4971,10 +4969,9 @@ manager_radio_user_toggled (NMManager *self,
 		                                "main", rstate->key,
 		                                G_TYPE_BOOLEAN, (gpointer) &enabled,
 		                                &error)) {
-			_LOGW (LOGD_CORE, "writing to state file %s failed: (%d) %s.",
+			_LOGW (LOGD_CORE, "writing to state file %s failed: %s",
 			       priv->state_file,
-			       error ? error->code : -1,
-			       (error && error->message) ? error->message : "unknown");
+			       error->message);
 			g_clear_error (&error);
 		}
 	}
diff --git a/src/nm-policy.c b/src/nm-policy.c
index 68e50a1c1a..b54468167c 100644
--- a/src/nm-policy.c
+++ b/src/nm-policy.c
@@ -697,8 +697,8 @@ auto_activate_device (gpointer user_data)
 		                                     &error)) {
 			nm_log_info (LOGD_DEVICE, "Connection '%s' auto-activation failed: (%d) %s",
 			             nm_settings_connection_get_id (best_connection),
-			             error ? error->code : -1,
-			             error ? error->message : "(none)");
+			             error->code,
+			             error->message);
 			g_error_free (error);
 		}
 		g_object_unref (subject);
@@ -1090,8 +1090,8 @@ activate_secondary_connections (NMPolicy *policy,
 		else {
 			nm_log_warn (LOGD_DEVICE, "Secondary connection '%s (%s)' auto-activation failed: (%d) %s",
 			             nm_settings_connection_get_id (settings_con), sec_uuid,
-			             error ? error->code : 0,
-			             (error && error->message) ? error->message : "unknown");
+			             error->code,
+			             error->message);
 			g_clear_error (&error);
 			success = FALSE;
 			break;
diff --git a/src/ppp-manager/nm-pppd-plugin.c b/src/ppp-manager/nm-pppd-plugin.c
index be4dd1855b..4c16f1f0f1 100644
--- a/src/ppp-manager/nm-pppd-plugin.c
+++ b/src/ppp-manager/nm-pppd-plugin.c
@@ -302,10 +302,9 @@ get_credentials (char *username, char *password)
 	                              G_DBUS_CALL_FLAGS_NONE, -1,
 	                              NULL, &err);
 	if (!ret) {
-		g_warning ("nm-ppp-plugin: (%s): could not get secrets: (%d) %s",
+		g_warning ("nm-ppp-plugin: (%s): could not get secrets: %s",
 		           __func__,
-		           err ? err->code : -1,
-		           err->message ? err->message : "(unknown)");
+		           err->message);
 		g_error_free (err);
 		return -1;
 	}
diff --git a/src/settings/nm-agent-manager.c b/src/settings/nm-agent-manager.c
index bc09e03167..455871de12 100644
--- a/src/settings/nm-agent-manager.c
+++ b/src/settings/nm-agent-manager.c
@@ -263,8 +263,8 @@ agent_register_permissions_done (NMAuthChain *chain,
 	if (error) {
 		local = g_error_new (NM_AGENT_MANAGER_ERROR,
 		                     NM_AGENT_MANAGER_ERROR_PERMISSION_DENIED,
-		                     "Failed to request agent permissions: (%d) %s",
-		                     error->code, error->message);
+		                     "Failed to request agent permissions: %s",
+		                     error->message);
 		g_dbus_method_invocation_take_error (context, local);
 	} else {
 		agent = nm_auth_chain_steal_data (chain, "agent");
@@ -987,9 +987,9 @@ _con_get_request_start_validated (NMAuthChain *chain,
 	req->con.chain = NULL;
 
 	if (error) {
-		_LOGD (req->current, "agent "LOG_REQ_FMT" MODIFY check error: (%d) %s",
+		_LOGD (req->current, "agent "LOG_REQ_FMT" MODIFY check error: %s",
 		       LOG_REQ_ARG (req),
-		       error->code, error->message ? error->message : "(unknown)");
+		       error->message);
 		/* Try the next agent */
 		request_next_agent (req);
 	} else {
diff --git a/src/settings/nm-settings-connection.c b/src/settings/nm-settings-connection.c
index a1695b3461..10aa77ab41 100644
--- a/src/settings/nm-settings-connection.c
+++ b/src/settings/nm-settings-connection.c
@@ -883,10 +883,8 @@ new_secrets_commit_cb (NMSettingsConnection *self,
                        GError *error,
                        gpointer user_data)
 {
-	if (error) {
-		_LOGW ("Error saving new secrets to backing storage: (%d) %s",
-		       error->code, error->message ? error->message : "(unknown)");
-	}
+	if (error)
+		_LOGW ("Error saving new secrets to backing storage: %s", error->message);
 }
 
 static void
@@ -1086,19 +1084,17 @@ get_secrets_done_cb (NMAgentManager *manager,
 			}
 
 		} else {
-			_LOGD ("(%s:%p) failed to update with agent secrets: (%d) %s",
+			_LOGD ("(%s:%p) failed to update with agent secrets: %s",
 			       setting_name,
 			       info,
-			       local ? local->code : -1,
-			       (local && local->message) ? local->message : "(unknown)");
+			       local->message);
 		}
 		g_variant_unref (filtered_secrets);
 	} else {
-		_LOGD ("(%s:%p) failed to update with existing secrets: (%d) %s",
+		_LOGD ("(%s:%p) failed to update with existing secrets: %s",
 		       setting_name,
 		       info,
-		       local ? local->code : -1,
-		       (local && local->message) ? local->message : "(unknown)");
+		       local->message);
 	}
 
 	applied_connection = info->applied_connection;
@@ -2163,7 +2159,7 @@ nm_settings_connection_update_timestamp (NMSettingsConnection *self,
 	/* Save timestamp to timestamps database file */
 	timestamps_file = g_key_file_new ();
 	if (!g_key_file_load_from_file (timestamps_file, SETTINGS_TIMESTAMPS_FILE, G_KEY_FILE_KEEP_COMMENTS, &error)) {
-		if (!(error->domain == G_FILE_ERROR && error->code == G_FILE_ERROR_NOENT))
+		if (!g_error_matches (error, G_FILE_ERROR, G_FILE_ERROR_NOENT))
 			_LOGW ("error parsing timestamps file '%s': %s", SETTINGS_TIMESTAMPS_FILE, error->message);
 		g_clear_error (&error);
 	}
@@ -2172,7 +2168,7 @@ nm_settings_connection_update_timestamp (NMSettingsConnection *self,
 	tmp = g_strdup_printf ("%" G_GUINT64_FORMAT, timestamp);
 	g_key_file_set_value (timestamps_file, "timestamps", connection_uuid, tmp);
 	g_free (tmp);
- 
+
 	data = g_key_file_to_data (timestamps_file, &len, &error);
 	if (data) {
 		g_file_set_contents (SETTINGS_TIMESTAMPS_FILE, data, len, &error);
@@ -2219,8 +2215,7 @@ nm_settings_connection_read_and_fill_timestamp (NMSettingsConnection *self)
 		priv->timestamp = timestamp;
 		priv->timestamp_set = TRUE;
 	} else {
-		_LOGD ("failed to read connection timestamp: (%d) %s",
-		       err->code, err->message);
+		_LOGD ("failed to read connection timestamp: %s", err->message);
 		g_clear_error (&err);
 	}
 	g_key_file_free (timestamps_file);
diff --git a/src/settings/nm-settings-plugin.c b/src/settings/nm-settings-plugin.c
index 2023bc17d5..7de7e597ff 100644
--- a/src/settings/nm-settings-plugin.c
+++ b/src/settings/nm-settings-plugin.c
@@ -175,5 +175,7 @@ nm_settings_plugin_add_connection (NMSettingsPlugin *config,
 	if (NM_SETTINGS_PLUGIN_GET_INTERFACE (config)->add_connection)
 		return NM_SETTINGS_PLUGIN_GET_INTERFACE (config)->add_connection (config, connection, save_to_disk, error);
 
+	g_set_error_literal (error, NM_SETTINGS_ERROR, NM_SETTINGS_ERROR_NOT_SUPPORTED,
+	                     "Plugin does not support adding connections");
 	return NULL;
 }
diff --git a/src/settings/nm-settings.c b/src/settings/nm-settings.c
index ee48e7119f..07a8c2e642 100644
--- a/src/settings/nm-settings.c
+++ b/src/settings/nm-settings.c
@@ -1120,7 +1120,7 @@ nm_settings_add_connection (NMSettings *self,
 		nm_log_dbg (LOGD_SETTINGS, "Failed to add %s/'%s': %s",
 		            nm_connection_get_uuid (connection),
 		            nm_connection_get_id (connection),
-		            add_error ? add_error->message : "(unknown)");
+		            add_error->message);
 		g_clear_error (&add_error);
 	}
 
@@ -1211,7 +1211,7 @@ pk_add_cb (NMAuthChain *chain,
 		error = g_error_new (NM_SETTINGS_ERROR,
 		                     NM_SETTINGS_ERROR_FAILED,
 		                     "Error checking authorization: %s",
-		                     chain_error->message ? chain_error->message : "(unknown)");
+		                     chain_error->message);
 	} else if (result != NM_AUTH_CALL_RESULT_YES) {
 		error = g_error_new_literal (NM_SETTINGS_ERROR,
 		                             NM_SETTINGS_ERROR_PERMISSION_DENIED,
@@ -1294,7 +1294,7 @@ nm_settings_add_connection_dbus (NMSettings *self,
 		error = g_error_new (NM_SETTINGS_ERROR,
 		                     NM_SETTINGS_ERROR_INVALID_CONNECTION,
 		                     "The connection was invalid: %s",
-		                     tmp_error ? tmp_error->message : "(unknown)");
+		                     tmp_error->message);
 		g_error_free (tmp_error);
 		goto done;
 	}
@@ -1625,7 +1625,7 @@ pk_hostname_cb (NMAuthChain *chain,
 		error = g_error_new (NM_SETTINGS_ERROR,
 		                     NM_SETTINGS_ERROR_FAILED,
 		                     "Error checking authorization: %s",
-		                     chain_error->message ? chain_error->message : "(unknown)");
+		                     chain_error->message);
 	} else if (result != NM_AUTH_CALL_RESULT_YES) {
 		error = g_error_new_literal (NM_SETTINGS_ERROR,
 		                             NM_SETTINGS_ERROR_PERMISSION_DENIED,
@@ -1896,7 +1896,7 @@ device_realized (NMDevice *device, GParamSpec *pspec, NMSettings *self)
 	if (!added) {
 		nm_log_warn (LOGD_SETTINGS, "(%s) couldn't create default wired connection: %s",
 		             nm_device_get_iface (device),
-		             (error && error->message) ? error->message : "(unknown)");
+		             error->message);
 		g_clear_error (&error);
 		return;
 	}
diff --git a/src/settings/plugins/ifupdown/nm-ifupdown-connection.c b/src/settings/plugins/ifupdown/nm-ifupdown-connection.c
index 19de1db625..93b106b8ea 100644
--- a/src/settings/plugins/ifupdown/nm-ifupdown-connection.c
+++ b/src/settings/plugins/ifupdown/nm-ifupdown-connection.c
@@ -95,11 +95,10 @@ constructor (GType type,
 	}
 
 	if (!ifupdown_update_connection_from_if_block (NM_CONNECTION (object), priv->ifblock, &error)) {
-		nm_log_warn (LOGD_SETTINGS, "%s.%d - invalid connection read from /etc/network/interfaces: (%d) %s",
+		nm_log_warn (LOGD_SETTINGS, "%s.%d - invalid connection read from /etc/network/interfaces: %s",
 		             __FILE__,
 		             __LINE__,
-		             error ? error->code : -1,
-		             error && error->message ? error->message : "(unknown)");
+		             error->message);
 		goto err;
 	}
 
diff --git a/src/settings/plugins/keyfile/plugin.c b/src/settings/plugins/keyfile/plugin.c
index 29a1141b8e..6003c7457f 100644
--- a/src/settings/plugins/keyfile/plugin.c
+++ b/src/settings/plugins/keyfile/plugin.c
@@ -404,10 +404,9 @@ read_connections (NMSettingsPlugin *config)
 
 	dir = g_dir_open (nm_keyfile_plugin_get_path (), 0, &error);
 	if (!dir) {
-		nm_log_warn (LOGD_SETTINGS, "keyfile: cannot read directory '%s': (%d) %s",
+		nm_log_warn (LOGD_SETTINGS, "keyfile: cannot read directory '%s': %s",
 		             nm_keyfile_plugin_get_path (),
-		             error ? error->code : -1,
-		             error && error->message ? error->message : "(unknown)");
+		             error->message);
 		g_clear_error (&error);
 		return;
 	}
diff --git a/src/vpn-manager/nm-vpn-connection.c b/src/vpn-manager/nm-vpn-connection.c
index 653b997231..54d20b1914 100644
--- a/src/vpn-manager/nm-vpn-connection.c
+++ b/src/vpn-manager/nm-vpn-connection.c
@@ -2224,8 +2224,8 @@ get_secrets_cb (NMSettingsConnection *connection,
 		return;
 
 	if (error && priv->secrets_idx >= SECRETS_REQ_NEW) {
-		_LOGE ("Failed to request VPN secrets #%d: (%d) %s",
-		       priv->secrets_idx + 1, error->code, error->message);
+		_LOGE ("Failed to request VPN secrets #%d: %s",
+		       priv->secrets_idx + 1, error->message);
 		_set_vpn_state (self, STATE_FAILED, NM_VPN_CONNECTION_STATE_REASON_NO_SECRETS, FALSE);
 		return;
 	}