I ran into this too. I was able to work around it by switching the Jupyter extension to the pre-release version (which was a suggestion in a different question that I can't find anymore).
Answer from Alex Trzyna on Stack OverflowI ran into this too. I was able to work around it by switching the Jupyter extension to the pre-release version (which was a suggestion in a different question that I can't find anymore).
solved downgrading to previous version (November 2022) then updating to latest version again. Running same Python and Jupyter version. Good luck
Jupyter for vscode continues to be slow (for large notebooks with mardown cells & large outputs)
Jupyter notebook stuck loading, not showing content, in VSCode
Jupyter notebook in Vs code STUCK. Malfunctioning
Jupyter Notebook extension Visual Studio Code stuck "connecting to kernel" - Stack Overflow
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It's not the Visual Studio Code update. I've been experimenting on a virtual machine, after my students started complaining this week that their Jupyter Notebooks stopped working...
I've tried downgrading Visual Studio Code, but that didn't solve the problem, so I started looking somewhere else.
As far as I know right now, the problem lies in the Jupyter-extension.
I have first disabled the Auto Update for the Jupyter-extension.
Next, I have downgraded the extension to version 2025.7.0, and it works again.
For good measure, I've then tried to update to version 2025.8.0: it also works.
But, when using version 2025.9.0: it breaks!
So what I would recommend:
In the Extensions-tab, disable Auto Update for the Jupyter extension.
Then use the Install Specific Version-menu to install version 2025.8.0.
After further testing:
The alternative is to Switch to Pre-Release Version, at least version 2025.10.2025101001. That also works.
UPDATE 2025-10-16:
Jupyter extension version 2025.9.1 has been released. This fixes the issue as well.
It seems to be an issue with the version 7.0.0 of the ipykernel python package. The jupyter notebook extension in vscode as well as the jupyter notebook in the browser get stuck in kernel connecting state when a cell is executed. On installing ipykernel==6.30.1, which is the version before 7.0.0, I don't face this issue in vscode or jupyter notebook in browser.
I have created an issue for the same: https://github.com/ipython/ipykernel/issues/1445
Hence I think we have to use ipykernel==6.30.1 until the issue is fixed. You can install it by running
pip install ipykernel==6.30.1
P.S.: ipykernel 7.0.1 has been released and it fixes this issue.
Intellisense in VSCode is quite annoying when working in Python. Every time I type a quote character I get a window popup that asks me if I want to type "ArithmeticError". I googled and found this solution:
https://stackoverflow.com/questions/72824819/vscode-autocomplete-intellisense-in-jupyter-notebook-when-starting-string-lit
The problem is that when I added "jupyter.pythonCompletionTriggerCharacters": ".%", to my settings.json and restarted VSCode, I lost the ability to open .ipynb files. When I try I get an error dialog that says "Unable to open / Could not initialize webview: Error: Coult not register service worker: Invalid State Error: Failed to register a ServiceWorker: The document is in an invalid state..}"
Any idea if this can be fixed (without undoing my changes to settings.json)? Thank you
If Python extension is available, (if not install that extension) in VSCode, while the jupyter style file (cells beginning with # %%) is active:
- Press Ctrl+Shift+P
- Type: Export Current Python File as Jupyter Notebook
An easy way to fix this should be to save the file with an .ipynb ending, vs-code should then automatically start the notebook extension. You can also make sure that you activated a Python environment, then Python: Create New Blank Jupyter Notebook should appear.
An alternative I would recommend is editing notebooks following this guide in the vs-code documentation
Error which I see after toggling Developer mode.
Please help!