gh-135683: Honor raiseExceptions when opening the file fails in FileHandler (GH-154542)

FileHandler and WatchedFileHandler opened the file outside the try block
that reports errors via handleError(), so an error while opening the file
was raised instead of being handled, ignoring raiseExceptions.

Co-authored-by: Vinay Sajip <vinay_sajip@yahoo.co.uk>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

Lib/logging/__init__.py

@@ -1263,7 +1263,12 @@ def emit(self, record):
         """
         if self.stream is None:
             if self.mode != 'w' or not self._closed:
-                self.stream = self._open()
+                # Report an error while opening the file, like emit errors.
+                try:
+                    self.stream = self._open()
+                except Exception:
+                    self.handleError(record)
+                    return
         if self.stream:
             StreamHandler.emit(self, record)
 

Lib/logging/handlers.py

@@ -563,8 +563,13 @@ def emit(self, record):
         If underlying file has changed, reopen the file before emitting the
         record to it.
         """
-        self.reopenIfNeeded()
-        logging.FileHandler.emit(self, record)
+        # Report an error while reopening the file, like emit errors.
+        try:
+            self.reopenIfNeeded()
+        except Exception:
+            self.handleError(record)
+        else:
+            logging.FileHandler.emit(self, record)
 
 
 class SocketHandler(logging.Handler):

Lib/test/test_logging.py

@@ -6503,6 +6503,46 @@ def test_emit_after_closing_in_write_mode(self):
         with open(self.fn) as fp:
             self.assertEqual(fp.read().strip(), '1')
 
+    def _check_open_error(self, h):
+        # gh-135683: an error while opening the file in emit() respects
+        # raiseExceptions, like an error during the actual write.
+        r = logging.makeLogRecord({})
+        old_raise = logging.raiseExceptions
+        self.addCleanup(setattr, logging, 'raiseExceptions', old_raise)
+
+        logging.raiseExceptions = True
+        with support.captured_stderr() as stderr:
+            h.handle(r)
+        self.assertIn('\nFileNotFoundError:', stderr.getvalue())
+
+        logging.raiseExceptions = False
+        with support.captured_stderr() as stderr:
+            h.handle(r)
+        self.assertEqual('', stderr.getvalue())
+
+    def test_emit_open_error(self):
+        # FileHandler with delay: the failing open happens in emit().
+        d = tempfile.mkdtemp()
+        self.addCleanup(os_helper.rmtree, d)
+        h = logging.FileHandler(os.path.join(d, 'missing', 'a.log'),
+                                encoding='utf-8', delay=True)
+        self.addCleanup(h.close)
+        self._check_open_error(h)
+
+    @unittest.skipIf(os.name == 'nt',
+                     'WatchedFileHandler not appropriate for Windows.')
+    def test_emit_reopen_error(self):
+        # WatchedFileHandler: reopenIfNeeded() fails after the dir is removed.
+        d = tempfile.mkdtemp()
+        self.addCleanup(os_helper.rmtree, d)
+        subdir = os.path.join(d, 'sub')
+        os.mkdir(subdir)
+        h = logging.handlers.WatchedFileHandler(
+            os.path.join(subdir, 'b.log'), encoding='utf-8')
+        self.addCleanup(h.close)
+        os_helper.rmtree(subdir)
+        self._check_open_error(h)
+
 class RotatingFileHandlerTest(BaseFileTest):
     def test_should_not_rollover(self):
         # If file is empty rollover never occurs

Misc/NEWS.d/next/Library/2026-07-23-14-13-39.gh-issue-135683.droBu7.rst

@@ -0,0 +1,3 @@
+:class:`logging.FileHandler` and :class:`logging.handlers.WatchedFileHandler`
+now honor :data:`logging.raiseExceptions` for errors that occur while opening
+the file, like for other errors during logging.