Description

tonghuaroot

opened on Jul 10, 2026

Issue body actions

Bug report

Bug description:

IDLE raises an uncaught traceback when a file that is open in the editor is deleted or renamed by another program and the IDLE window is then refocused.

EditorWindow.focus_in_event runs on every <FocusIn> event and calls EditorWindow.last_mtime, which calls os.path.getmtime(self.io.filename) with no error handling. When the open file has been removed or renamed, getmtime raises FileNotFoundError, which escapes the Tk event handler and breaks the modified-on-disk reload check.

Reproduction

Open a file in the IDLE editor, delete or rename it in another program, then click back into the IDLE window. A traceback like this reaches the console and the reload check stops working:

FileNotFoundError: [Errno 2] No such file or directory: '.../somefile.py'

The same call reproduced without a GUI:

import os, tempfile, types
from idlelib.editor import EditorWindow

with tempfile.TemporaryDirectory() as d:
    path = os.path.join(d, 'gone.py')
    open(path, 'w').close()
    mtime = os.path.getmtime(path)
    os.remove(path)
    stub = types.SimpleNamespace(io=types.SimpleNamespace(filename=path), mtime=mtime)
    EditorWindow.last_mtime(stub)   # raises FileNotFoundError on the main branch

Suggested fix

Guard os.path.getmtime in last_mtime with try/except OSError and return the last known mtime, so focus_in_event sees no change and does not prompt to reload a file that is gone.

CPython versions tested on:

3.16, CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-153480: Stop IDLE crashing when a file open in the editor is deleted #153481
• [3.14] gh-153480: Stop IDLE crashing when a file open in the editor is deleted (GH-153481) #158262
• [3.13] gh-153480: Stop IDLE crashing when a file open in the editor is deleted (GH-153481) #158263
• [3.15] gh-153480: Stop IDLE crashing when a file open in the editor is deleted (GH-153481) #158264

Activity

1. tonghuaroot

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Jul 10, 2026
2. StanFromIreland

   added

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   topic-IDLE

   on Jul 10, 2026
3. StanFromIreland

   added this to IDLE Issueson Jul 10, 2026
4. terryjreedy commented on Jul 10, 2026

   

   terryjreedy

   on Jul 10, 2026

   Member

   More actions

   I choose the IDLE Issues topic "File save" as the closest because this is not about editing but about interaction with the external filesystem. I suspect that there could also be problems if Shell or an output window have been 'saved as'.

   Reacted by tonghuaroot (童话)
5. terryjreedy

   added

   type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump

   on Aug 7, 2026
6. terryjreedy

   moved this to In Progress in IDLE Issueson Aug 7, 2026
7. serhiy-storchaka commented on Sep 15, 2026

   

   serhiy-storchaka

   on Sep 15, 2026

   Member

   More actions

   This is worse than a traceback on FocusIn: the same last_mtime() runs from set_saved(True) inside EditorWindow.__init__, so opening a file that does not exist yet — python -m idlelib new.py, the usual way to start a new script — aborts IDLE at startup with FileNotFoundError. Regression from gh-94523; affects 3.13.15, 3.14.7, 3.15.0b1 and main.

   Traceback: pyshell.main → filelist.open → EditorWindow.__init__ (editor.py:242) → iomenu.set_filename → set_saved → editor.set_saved (1033) → last_mtime (1121) → os.path.getmtime.

   Proposed behavior: last_mtime() returns None when there is no file or it cannot be stat'ed (not 0, which is a valid mtime on filesystems without timestamps). If a file that was there is gone on FocusIn, ask Close / Save As / Ignore (default Save As); Ignore marks the window unsaved and resets the stored mtime to None so the question is asked once. This is an approximate plan; details can be changed later. See the review on #153481.
8. serhiy-storchaka

   added

   3.13only security fixesonly security fixes

   on Sep 15, 2026
9. serhiy-storchaka

   changed the title [-]IDLE crashes when a file open in the editor is deleted or renamed externally[/-] [+]IDLE fails to start or raises when an editor window's file does not exist[/+] on Sep 15, 2026
10. serhiy-storchaka

    added

    3.14bugs and security fixesbugs and security fixes

    3.15bugs and security fixesbugs and security fixes

    on Sep 15, 2026
11. tonghuaroot

    added 3 commits that reference this issue on Sep 17, 2026

    pythongh-153480: Return None from last_mtime() and handle a deleted file

    a57c59b

    pythongh-153480: Clear mtime in the deleted-file dialog before Save As

    ceffab2

    pythongh-153480: Clear mtime before the deleted-file dialog for all c…

    9cabce6
12. terryjreedy

    added 3 commits that reference this issue on Sep 27, 2026

    gh-153480: Stop IDLE crashing when a file open in the editor is delet…

    6af40a6

    [3.13] gh-153480: Stop IDLE crashing when a file open in the editor i…

    694e737

    [3.14] gh-153480: Stop IDLE crashing when a file open in the editor i…

    cbc7753
13. terryjreedy

    closed this as completedon Sep 27, 2026
14. terryjreedy

    added a commit that references this issue on Oct 9, 2026

    [3.15] gh-153480: Stop IDLE crashing when a file open in the editor i…

    251e132

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