Jupyter Notebook extension Visual Studio Code stuck "connecting to kernel"

Question

I use Python 3.11.1 and Jupyter Notebook to run code selections or lines in the Interactive Window for debugging or coding purposes.

A few days ago, everything was working fine, and I didn't have any issues running my code. However, after being away for two days, when I opened my project again and tried to run my code starting with importing pandas in the Interactive Window, it kept getting stuck at "Connecting to kernel".

I’ve already performed a clean uninstall and reinstalled Visual Studio Code, Jupyter, and Python, but the issue remains the same. Could this problem be caused by the September 2025 Visual Studio Code update (version 1.105), released on October 9th, 2025?

Answer 1

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.

Answer 2

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.