Pylance crashes at startup making Cursor unusable for Python programming.
Steps to Reproduce
Start cursor.
Observe the crash.
Sigh and sip coffee.
The end of the error log looks like this:
untitled:/Interactive-1.interactive.py
at _0x6c33a1 (/Users/username/.cursor/extensions/ms-python.vscode-pylance-2024.8.1/dist/server.bundle.js:1:920305)
at _0x965717 (/Users/username/.cursor/extensions/ms-python.vscode-pylance-2024.8.1/dist/server.bundle.js:1:924945)
at _0x263d8 (/Users/username/.cursor/extensions/ms-python.vscode-pylance-2024.8.1/dist/server.bundle.js:1:925386)
at /Users/username/.cursor/extensions/ms-python.vscode-pylance-2024.8.1/dist/server.bundle.js:1:851177
2025-08-11 09:31:59.127 [info] [Error - 09:31:59] Server process exited with code 1.
2025-08-11 09:31:59.129 [info] [Error - 09:31:59] Pylance has crashed 5 times in the last 3 minutes. Pylance will not be restarted. Please check [this link](https://aka.ms/AApf7ox) for more details.
Expected Behavior
Cursor works.
Operating System
MacOS
Current Cursor Version (Menu → About Cursor → Copy)
Hum, after some fiddling around, I realised this was caused by an interactive Python window (i.e. this kind of stuff, Python Interactive window ). Simply closing the window and restarting Cursor did the trick.
Ok, Pylance was automatically installed from my VSCode setup. I later saw in the extensions that Pylance had messages, and upon clicking on this “messages” link, it brought me to the Anysphere install page.
I uninstalled Pylance and replaced it with Anysphere, everything is working now, thanks!
Perhaps you could add a check upon importing extensions from VSCode at Cursor’s first install, and display warnings for extensions with known incompatibilities with Cursor? (such as Pylance)
This is not related to the original bug report, please open a new issue and fill-in a proper bug report with your Cursor version, config file, operating system, installed extensions, and any relevant info. This likely is a bug and needs some investigation (maybe you fiddled with your config file in the first place, breaking Cursor’s default config somehow, idk).
Anyway, this thread is not the place to discuss it. This forum is not your local bar where you can slam the door and rant around anywhere. While your frustration is understandable, you likely entered a non-default case, as JPNB Python lang support seems to work out of the box for most users.
FYI, JPNB support is awful in Cursor, with LLMs being dramatically incompetent at working within one, this is a well-known issue, e.g.:
and typing “Jupyter” in this forum’s search bar can give you an idea how bad this is.
What I would recommend you to do if you intend on using Cursor with JPNB is to use VSCode interactive mode. This lead you to have one window with your code and cells, and another one with the cells’ output. A tad cumbersome, but it’s the best option that we found so far in my team. This also has the advantage that cells’ output is not saved in the original code file, which is thus a pure python script (give or take a few %%), ideal for gitting it.
