[Bug] Jupyter Notebooks & AI Panel broken after upgrading to Cursor 3

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26

Hope Cursor can update and fix this soon. Data science workflows rely heavily on Jupyter..

27

@Sergii-L Unfortunately, chats and agent history from Cursor 3 arenā€™t compatible with version 2.6.22. They use different state.vscdb formats. If you renamed the %APPDATA%\Cursor folder to Cursor_backup, your v3 data is still there in Cursor_backup. You can switch back to Cursor 3 and rename Cursor_backup back to Cursor, and your chats should show up.

Instead of a full rollback, try the cursor-socket symlink fix that helped other Windows users:

  • Open PowerShell as admin
  • Check the folder contents:
    dir "$env:LOCALAPPDATA\Programs\cursor\resources\app\extensions\cursor-socket"
  • If you see dist\ but not out\, create a symlink:
    cd "$env:LOCALAPPDATA\Programs\cursor\resources\app\extensions\cursor-socket"
New-Item -ItemType SymbolicLink -Name "out" -Target "dist"
  • Restart Cursor.

If youā€™re using the system setup, the path will be C:\Program Files\cursor\... instead of $env:LOCALAPPDATA\Programs\cursor\....

28

@VasilisT The same symlink fix above might help make the solution stick across restarts. Please try it and let me know if it still works after restarting.

29

@Shaoyang_Xue The team is aware of this issue. Thereā€™s no exact ETA yet, but your reports help with prioritization. If the workaround of disabling the Python Environment extension works for Jupyter, use that for now. Also try the cursor-socket symlink fix above, it may fix the root cause.

Let me know how it goes.

30

Previously, even after disabling the Python Environment extension, I occasionally experienced freezes with both Jupyter and the Agent upon restarting Cursor.

You are correct, the out folder was indeed missing in that directoryļ¼ˆC:\Program Files\cursor\resources\app\extensions\cursor-socketļ¼‰. I have followed your instructions to create the symbolic link. I will continue using Cursor over the next couple of days to monitor the situation and see if the issue persists.

31

Have had the same issue since release on my Mac. I kept rolling back to previous version, but eventually it would automatically update to cursor 3 even though I kept clicking ā€œLaterā€ on the update popup. Accidentally found a fix that has worked: When opening Cursor on a ipynb editor, I would get the issue. While ipynb is loading (forever), switch to another file (I opened a sql file, which opened correctly). With the editor on the sql tab, I quit cursor (cmd+Q), reopen, and then everything loaded perfectly.
I did some tests and itā€™s easy to reproduce. It seems like, when starting Cursor directly on a ipynb file, the IDE doesnā€™t load properly (not even terminal). when starting on another kind of file, it loads properly and you can access your ipynb files afterwards

33

Thank you, I have tried that solution, the out symlink file has been generated, but the issue still exist

34

Thank you, that trick worked on windows too! It takes some time to load but it worked! A good temporary solution until the issue properly fixed on another version

35

@deanrie thanks - but it did not work what for me ..

36

Indeed, it works. Takes some 30s to load but works!! Thanks for discovering and sharing @javidv

39

This worked for me as well, thank you so much!

40

Clearing the cash worked for me on Mac, here are the steps:

Close Cursor first, then open Terminal and run:

rm -rf ~/Library/Application\ Support/Cursor/CachedExtensions
rm -rf ~/Library/Application\ Support/Cursor/CachedExtensionVSIXs

Then relaunch Cursor and try opening a notebook.

41

still happening on Mac, i too have found that simply focusing on any other file, then doing a reload window works fine.

still very annoying, would like to get it resoved

42

I downloaded 3 for windows. I see .py files as usual, but for .ipynb it is loaded for ever. Then I switched back. Chose composer 2 as my agent, but it keeps jumping to 3 after computer re-start.

43

This is the only way!!! Cheers mate!

44

Thanks. I donā€™t know why, but it helped.

45

Please fix the bug ASAP.

46

Hey @Max_Wang, this is a known bug and itā€™s being tracked, but thereā€™s no specific ETA for a fix yet.

For now, the thread has a couple of working workarounds that several users have confirmed:

If neither helps, share your Cursor version and OS version and weā€™ll see what else we can try.

47

The second workaround solved the problem. Thank you.

48

+1 for this bug. This is really annoying