# \[BUG\] FSRS Desired Retention Simulator (Help Me Decide) Crash **URL:** \ **Category:** Help\ **Created:** [June 16, 2026, 8:32pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125 "2026-06-16T20:32:26Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![jonakashima](https://avatars.discourse-cdn.com/v4/letter/j/e495f1/32.png) [@jonakashima](https://forums.ankiweb.net/u/jonakashima)\ **Post date:** [June 16, 2026, 8:32pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/1 "2026-06-16T20:32:27Z")
When a deck has the default FSRS parameters, the Help Me Decide simulator gets stuck on processing after hitting simulate, it then gives this error and debug info ```auto Error: 404: Invalid path: _anki/latestProgress ``` ```auto Anki 26.05 (e64c6b1a) (ao) Python 3.13.13 Qt 6.11.0 PyQt 6.11.0 Platform: Windows-11-10.0.26200-SP0 Traceback (most recent call last): File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\progress.py", line 121, in handler File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\main.py", line 1578, in on_periodic_backup_timer File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\main.py", line 1629, in create_backup_with_progress File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init.py", line 263, in run_in_background File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init_.py", line 281, in _run File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 113, in with_progress File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 71, in run_in_background File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 148, in on_closures_pending File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 88, in File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init.py", line 259, in wrapped_done File "concurrent\futures_base.py", line 449, in result File "concurrent\futures_base.py", line 401, in _get_result File "concurrent\futures\thread.py", line 59, in run File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init.py", line 243, in wrapped_op File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\deckbrowser.py", line 163, in get_data File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki\scheduler\base.py", line 79, in deck_due_tree File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki_backend_generated.py", line 386, in deck_tree File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki_backend.py", line 162, in _run_command pyo3_runtime.PanicException: called Result::unwrap() on an Err value: PoisonError { .. } ``` ---
**Author:** ![VLCO](https://avatars.discourse-cdn.com/v4/letter/v/5e9695/32.png) [@VLCO](https://forums.ankiweb.net/u/VLCO)\ **Post date:** [June 20, 2026, 2:32am UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/2 "2026-06-20T02:32:49Z")
After updating to 26.05, I keep having problems getting the FSRS Desired Retention Simulator to work for some decks. Whenever I try to simulate, it shows `Error: 404: Invalid path:` _anki/latestProgress`. The only decks affected are ones for which I have the `Ignore cards reviewed before` filled (set to `01/05/2026`). The following is the debug info: ```auto Anki 26.05 (e64c6b1a) Python 3.13.13 Qt 6.11.0 PyQt 6.11.0 Platform: Windows-11-10.0.26200-SP0 Traceback (most recent call last): File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 148, in on_closures_pending File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 88, in File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\taskman.py", line 111, in wrapped_done File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init.py", line 259, in wrapped_done File "concurrent\futures_base.py", line 449, in result File "concurrent\futures_base.py", line 401, in _get_result File "concurrent\futures\thread.py", line 59, in run File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\operations_init.py", line 243, in wrapped_op File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\aqt\main.py", line 1596, in backup File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki\collection.py", line 343, in create_backup File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki_backend_generated.py", line 172, in create_backup File "D:\a\anki\anki\out\installer\build\anki\windows\app\src\app_packages\anki_backend.py", line 162, in _run_command pyo3_runtime.PanicException: called Result::unwrap() on an Err value: PoisonError { .. } ``` ---
**Author:** ![arijun](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@arijun](https://forums.ankiweb.net/u/arijun)\ **Post date:** [July 9, 2026, 4:52pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/3 "2026-07-09T16:52:06Z")
After running the Simulate button on the FSRS desired retention simulator, it thinks for a bit before crashing with a fatal error, which leads to a segfault. It gives me the error “Error: 404: Invalid path: \_anki/latestProgress”, with the following traceback: ```auto Anki 26.05 (e64c6b1a) (ao)Python 3.13.11 Qt 6.11.0 PyQt 6.11.0Platform: macOS-15.7.3-arm64-arm-64bit-Mach-O Traceback (most recent call last):File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/progress.py", line 121, in handlerFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/main.py", line 1578, in on_periodic_backup_timerFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/main.py", line 1629, in _create_backup_with_progressFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/init.py", line 263, in run_in_backgroundFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/init.py", line 281, in _runFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 113, in with_progressFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 71, in run_in_backgroundFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 148, in _on_closures_pendingFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 88, in File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/init.py", line 259, in wrapped_doneFile "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/_base.py", line 449, in resultreturn self.__get_result() ~~~~~~~~~~~~~~~~~ ^^File "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/_base.py", line 401, in__get_resultraise self._exceptionFile "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/thread.py", line 59, in runresult = self.fn(*self.args, **self.kwargs)File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/init.py", line 243, in wrapped_opFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/deckbrowser.py", line 163, in get_dataFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/scheduler/base.py", line 79, in deck_due_treeFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/_backend_generated.py", line 386, in deck_treeFile "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/_backend.py", line 162, in _run_commandpyo3_runtime.PanicException: called Result::unwrap() on an Err value: PoisonError { .. } ``` This is followed by a SIGSEGV: ```auto ------------------------------------- Translated Report (Full Report Below) ------------------------------------- Process: Anki [3090] Path: /Applications/Anki.app/Contents/MacOS/Anki Identifier: net.ankiweb.anki Version: 26.5 (1) Code Type: ARM-64 (Native) Parent Process: launchd [1] User ID: 501 Date/Time: 2026-07-09 12:19:55.3782 -0400 OS Version: macOS 15.7.3 (24G419) Report Version: 12 Anonymous UUID: 6DA7E170-71BD-1CB8-49FB-9A0C14D599B9 Sleep/Wake UUID: 45F88728-0998-4720-908C-F82CC60E21BD Time Awake Since Boot: 1300000 seconds Time Since Wake: 1735 seconds System Integrity Protection: enabled Crashed Thread: 0 CrBrowserMain Dispatch queue: com.apple.main-thread Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x0000000000000010 Exception Codes: 0x0000000000000001, 0x0000000000000010 Termination Reason: Namespace SIGNAL, Code 11 Segmentation fault: 11 Terminating Process: exc handler [3090] VM Region Info: 0x10 is not in any region. Bytes before following region: 4369203184 REGION TYPE START - END [VSIZE] PRT/MAX SHRMOD REGION DETAIL UNUSED SPACE AT START ---> __TEXT 1046cc000-1046d0000 [16K] r-x/r-x SM=COW /Applications/Anki.app/Contents/MacOS/Anki Thread 0 Crashed:: CrBrowserMain Dispatch queue: com.apple.main-thread 0 QtWebEngineCore 0x14d9fb500 QWebEnginePage::setVisible(bool) + 20 1 QtWebEngineWidgets.abi3.so 0x108f06794 sipQWebEngineView::hideEvent(QHideEvent*) + 148 2 QtWidgets 0x10bc13eb8 QWidget::event(QEvent*) + 132 3 QtWebEngineWidgets.abi3.so 0x108f04f3c sipQWebEngineView::event(QEvent*) + 224 4 QtWidgets 0x10bbc51a8 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 332 5 QtWidgets 0x10bbc6d98 QApplication::notify(QObject*, QEvent*) + 3484 6 QtWidgets.abi3.so 0x10cd44038 sipQApplication::notify(QObject*, QEvent*) + 248 7 QtCore 0x1099ada08 QCoreApplication::sendEvent(QObject*, QEvent*) + 172 8 QtWidgets 0x10bc12cd4 QWidgetPrivate::hideChildren(bool) + 1140 9 QtWidgets 0x10bc12c98 QWidgetPrivate::hideChildren(bool) + 1080 10 QtWidgets 0x10bc12758 QWidgetPrivate::hide_helper() + 288 11 QtWidgets 0x10bc137b0 QWidgetPrivate::setVisible(bool) + 984 12 QtWidgets 0x10bc13148 QWidget::setVisible(bool) + 792 13 QtWidgets 0x10bc13cc0 QWidgetPrivate::handleClose(QWidgetPrivate::CloseMode) + 488 14 QtWidgets 0x10bc2cb88 0x10bbb8000 + 478088 15 QtGui 0x10c4b9d88 QWindow::event(QEvent*) + 528 16 QtWidgets 0x10bbc51a8 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 332 17 QtWidgets 0x10bbc6200 QApplication::notify(QObject*, QEvent*) + 516 18 QtWidgets.abi3.so 0x10cd44038 sipQApplication::notify(QObject*, QEvent*) + 248 19 QtCore 0x1099adb34 QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) + 176 20 QtGui 0x10c45ce30 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) + 2444 21 QtGui 0x10c4c8434 0x10c3cc000 + 1033268 22 QtGui 0x10c4b8ff4 QWindow::close() + 132 23 QtWidgets 0x10bc01668 QWidget::~QWidget() + 932 24 QtWidgets.abi3.so 0x10cc8e550 sipQMainWindow::~sipQMainWindow() + 64 25 QtCore.abi3.so 0x1090a7d6c cleanup_qobject(_sipSimpleWrapper*, void*) + 224 26 sip.cpython-313-darwin.so 0x108b5e874 sip_api_visit_wrappers + 100 27 QtCore.abi3.so 0x1090a7618 cleanup_on_exit(_object*, _object*) + 16 28 Python 0x10598b094 cfunction_vectorcall_NOARGS + 100 29 Python 0x105b8b7f4 atexit_callfuncs + 128 30 Python 0x105b54bec _Py_Finalize + 180 31 Python 0x105b59338 Py_Exit + 64 32 Python 0x105b5dd44 _PyErr_PrintEx + 76 33 QtCore.abi3.so 0x1090a7e00 pyqt6_err_print() + 128 34 QtCore.abi3.so 0x1090b0298 PyQtSlotProxy::unislot(void**) + 112 35 QtCore.abi3.so 0x1090b01f4 PyQtSlotProxy::qt_metacall(QMetaObject::Call, int, void**) + 68 36 QtCore 0x109a026b8 0x109910000 + 992952 37 QtCore 0x109a15f80 QTimer::timerEvent(QTimerEvent*) + 204 38 QtCore.abi3.so 0x108f77660 sipQTimer::timerEvent(QTimerEvent*) + 148 39 QtCore 0x1099f9d54 QObject::event(QEvent*) + 104 40 QtCore.abi3.so 0x108f774ac sipQTimer::event(QEvent*) + 220 41 QtWidgets 0x10bbc51a8 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 332 42 QtWidgets 0x10bbc6200 QApplication::notify(QObject*, QEvent*) + 516 43 QtWidgets.abi3.so 0x10cd44038 sipQApplication::notify(QObject*, QEvent*) + 248 44 QtCore 0x1099ada08 QCoreApplication::sendEvent(QObject*, QEvent*) + 172 45 QtCore 0x109b5b284 QTimerInfoList::activateTimers() + 1268 46 libqcocoa.dylib 0x10e4bf8a8 0x10e4a8000 + 96424 47 CoreFoundation 0x19105ea64 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 48 CoreFoundation 0x19105e9f8 __CFRunLoopDoSource0 + 172 49 CoreFoundation 0x19105e764 __CFRunLoopDoSources0 + 232 50 CoreFoundation 0x19105d3b8 __CFRunLoopRun + 840 51 CoreFoundation 0x19105c9e8 CFRunLoopRunSpecific + 572 52 HIToolbox 0x19cafd27c RunCurrentEventLoopInMode + 324 53 HIToolbox 0x19cb004e8 ReceiveNextEventCommon + 676 54 HIToolbox 0x19cc8b484 _BlockUntilNextEventMatchingListInModeWithFilter + 76 55 AppKit 0x194f7da34 _DPSNextEvent + 684 56 AppKit 0x19591c940 -[NSApplication(NSEventRouting) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 688 57 libqcocoa.dylib 0x10e4c04e0 0x10e4a8000 + 99552 58 QtCore 0x1099b70f8 QEventLoop::exec(QFlags) + 588 59 QtCore 0x1099ad700 QCoreApplication::exec() + 228 60 QtWidgets.abi3.so 0x10ce4eb64 meth_QApplication_exec(_object*, _object*) + 96 61 Python 0x10598a384 cfunction_call + 116 62 Python 0x105ab19b8 _PyEval_EvalFrameDefault + 40016 63 Python 0x105aa53a8 PyEval_EvalCode + 132 64 Python 0x105a9f0f0 builtin_exec + 396 65 Python 0x10598afdc cfunction_vectorcall_FASTCALL_KEYWORDS + 88 66 Python 0x105ab1664 _PyEval_EvalFrameDefault + 39164 67 Anki 0x1046cd3d8 main + 2328 68 dyld 0x190bd2b98 start + 6076 ``` That report is truncated, if you need something else from it, let me know. As an aside, this forum is not good for bug reports. I tried to see if this bug was reported, but I can’t even tell what is a closed bug and what isn’t! ---
**Author:** ![BenJamesBen](https://avatars.discourse-cdn.com/v4/letter/b/13edae/32.png) [@BenJamesBen](https://forums.ankiweb.net/u/BenJamesBen)\ **Post date:** [July 9, 2026, 5:21pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/4 "2026-07-09T17:21:31Z")
Appears to be the same issue as: > [@\[BUG\] FSRS Desired Retention Simulator (Help Me Decide) Crash](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/2): > > After updating to 26.05, I keep having problems getting the FSRS Desired Retention Simulator to work for some decks. Whenever I try to simulate, it shows `Error: 404: Invalid path: \_anki/latestProgress. The only decks affected are ones for which I have the Ignore cards reviewed before filled (set to 01/05/2026). The following is the debug info: Anki 26.05 (e64c6b1a) Python 3.13.13 Qt 6.11.0 PyQt 6.11.0 Platform: Windows-11-10.0.26200-SP0 Traceback (most recent call last): File "D:\a\anki\anki\… (I previously tried but was not able to reproduce this problem behavior.) ---
**Author:** ![arijun](https://avatars.discourse-cdn.com/v4/letter/a/b5a626/32.png) [@arijun](https://forums.ankiweb.net/u/arijun)\ **Post date:** [July 11, 2026, 7:35pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/5 "2026-07-11T19:35:53Z")
Yes same cause it would seem, so thanks for finding that. I can give more information if you’re having trouble with repro. My bug was probably actually two bugs, and the second one wasn’t represented here; that the crash lead to a segfault. Maybe not as urgent (or worth opening a second report), since anki has already crashed before it segfaults, but worth noting. ---
**Author:** ![Altostratus](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Altostratus](https://forums.ankiweb.net/u/Altostratus)\ **Post date:** [July 29, 2026, 5:40am UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/6 "2026-07-29T05:40:46Z")
Hi, just had my first crash. Not sure where to post this. Thanks. ```auto Anki 26.05 (e64c6b1a) (ao) Python 3.13.11 Qt 6.11.0 PyQt 6.11.0 Platform: macOS-15.7.7-arm64-arm-64bit-Mach-O Traceback (most recent call last): File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 148, in _on_closures_pending File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 88, in File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/taskman.py", line 111, in wrapped_done File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/ __init__.py", line 259, in wrapped_done File "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/_base.py", line 449, in result return self.__get_result() ~~~~~~~~~~~~~~~~~ ^^ File "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/_base.py", line 401, in __get_result raise self._exception File "/Applications/Anki.app/Contents/Frameworks/Python.framework/Versions/3.13/lib/python3.13/concurrent/futures/thread.py", line 59, in run result = self.fn(*self.args, **self.kwargs) File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/operations/ __init__.py", line 243, in wrapped_op File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/aqt/main.py", line 1596, in backup File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/collection.py", line 343, in create_backup File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/_backend_generated.py", line 172, in create_backup File "/Users/runner/work/anki/anki/out/installer/build/anki/macos/app/Anki.app/Contents/Resources/app_packages/anki/_backend.py", line 162, in _run_command pyo3_runtime.PanicException: called `Result::unwrap()` on an `Err` value: PoisonError { .. } ``` ---
**Author:** ![Danika\_Dakika](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/danika_dakika/32/17815_2.png) [@Danika\_Dakika](https://forums.ankiweb.net/u/Danika_Dakika)\ **Post date:** [July 29, 2026, 7:24am UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/7 "2026-07-29T07:24:48Z")
Thanks. We’ve seen a few reports of this. ---
**Author:** ![abdo](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/abdo/32/654_2.png) [@abdo](https://forums.ankiweb.net/u/abdo)\ **Post date:** [July 29, 2026, 5:55pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/8 "2026-07-29T17:55:22Z")
Logged here: > > > \> When a deck has the default FSRS parameters, the Help Me Decide simulator gets… stuck on processing after hitting simulate, it then gives this error and debug info > \> Error: 404: Invalid path: \_anki/latestProgress > \> > \> Anki 26.05 (e64c6b1a) (ao) > \> Python 3.13.13 Qt 6.11.0 PyQt 6.11.0 > \> Platform: Windows-11-10.0.26200-SP0 > \> > \> Traceback (most recent call last): > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\progress.py", line 121, in handler > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\main.py", line 1578, in on\_periodic\_backup\_timer > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\main.py", line 1629, in create\_backup\_with\_progress > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\operations\_init.py", line 263, in run\_in\_background > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\operations\_init\_.py", line 281, in \_run > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\taskman.py", line 113, in with\_progress > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\taskman.py", line 71, in run\_in\_background > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\taskman.py", line 148, in on\_closures\_pending > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\taskman.py", line 88, in > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\operations\_init.py", line 259, in wrapped\_done > \> File "concurrent\\futures\_base.py", line 449, in result > \> File "concurrent\\futures\_base.py", line 401, in \_get\_result > \> File "concurrent\\futures\\thread.py", line 59, in run > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\operations\_init.py", line 243, in wrapped\_op > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\aqt\\deckbrowser.py", line 163, in get\_data > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\anki\\scheduler\\base.py", line 79, in deck\_due\_tree > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\anki\_backend\_generated.py", line 386, in deck\_tree > \> File "D:\\a\\anki\\anki\\out\\installer\\build\\anki\\windows\\app\\src\\app\_packages\\anki\_backend.py", line 162, in \_run\_command > \> pyo3\_runtime.PanicException: called Result::unwrap() on an Err value: PoisonError { .. } > \> > > Originally reported on https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125 ---
**Author:** ![A\_Blokee](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/a_blokee/32/17955_2.png) [@A\_Blokee](https://forums.ankiweb.net/u/A_Blokee)\ **Post date:** [July 31, 2026, 12:06pm UTC](https://forums.ankiweb.net/t/bug-fsrs-desired-retention-simulator-help-me-decide-crash/70125/9 "2026-07-31T12:06:32Z")
This bug should be fixed in the next update~