# A fatal error occurred on Anki

**URL:** <https://forums.ankiweb.net/t/a-fatal-error-occurred-on-anki/31508>\
**Category:** Help\
**Created:** [June 23, 2023, 8:45pm UTC](https://forums.ankiweb.net/t/a-fatal-error-occurred-on-anki/31508 "2023-06-23T20:45:50Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Oisin](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@Oisin](https://forums.ankiweb.net/u/Oisin)\
**Post date:** [June 23, 2023, 8:45pm UTC](https://forums.ankiweb.net/t/a-fatal-error-occurred-on-anki/31508/1 "2023-06-23T20:45:50Z")

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I recieved this message while using Anki. After opening it again, everything seems perfectly normal.

A fatal error occurred, and Anki must close. Please report this message on the forums.  
Anki 2.1.65 (aa9a734f) Python 3.9.15 Qt 6.4.3 PyQt 6.4.0  
Platform: Windows-10-10.0.22621  
Flags: frz=True ao=True sv=?  
Add-ons, last update check: 2023-06-22 11:39:19

Caught exception:  
Traceback (most recent call last):  
File “aqt.taskman”, line 122, in \_on\_closures\_pending  
File “aqt.taskman”, line 71, in   
File “aqt.taskman”, line 90, in wrapped\_done  
File “aqt.operations”, line 120, in wrapped\_done  
File “concurrent.futures.\_base”, line 439, in result  
File “concurrent.futures.\_base”, line 391, in \_\_get\_result  
File “concurrent.futures.thread”, line 58, in run  
File “aqt.operations”, line 105, in wrapped\_op  
File “aqt.operations.note”, line 22, in   
File “anki.collection”, line 566, in add\_note  
File “anki.\_backend\_generated”, line 609, in add\_note  
File “anki.\_backend”, line 150, in \_run\_command  
pyo3\_runtime.PanicException: assertion failed: `(left == right)`  
left: `1687552738792`,  
right: `0`

Traceback (most recent call last):  
File “aqt.browser.table.model”, line 103, in \_fetch\_row\_from\_backend  
File “anki.collection”, line 884, in browser\_row\_for\_id  
File “anki.\_backend\_generated”, line 1599, in browser\_row\_for\_id  
File “anki.\_backend”, line 150, in \_run\_command  
pyo3\_runtime.PanicException: called `Result::unwrap()` on an `Err` value: PoisonError { … }

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<div class="post-metadata">

**Author:** ![dae](https://sea2.discourse-cdn.com/flex002/user_avatar/forums.ankiweb.net/dae/32/65_2.png) [@dae](https://forums.ankiweb.net/u/dae)\
**Post date:** [June 26, 2023, 4:45am UTC](https://forums.ankiweb.net/t/a-fatal-error-occurred-on-anki/31508/2 "2023-06-26T04:45:56Z")

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If you find it keeps happening, please see if you’re able to reproduce it when add-ons are disabled.

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex002/uploads/anki2/original/1X/8f1279ababc5879d54e4838989f606cfe55af8c7.jpeg) [@system](https://forums.ankiweb.net/u/system)\
**Post date:** [July 26, 2023, 4:46am UTC](https://forums.ankiweb.net/t/a-fatal-error-occurred-on-anki/31508/3 "2023-07-26T04:46:30Z")

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