VS Code Stuck on "Detecting Kernel" After Latest Version Installation

Question

VS Code Stuck on "Detecting Kernel" After Latest Version Installation

guru charan 10

I recently installed the latest version of Visual Studio Code. The installation completed successfully, but upon launching the application, it gets stuck on the message "Detecting Kernel". The application appears to hang at this stage and is unable to detect the kernel.

Steps Taken:

Verified Python installation paths.

Tried restarting VS Code and the system.

No extensions or previous settings seem to interfere.

Impact: Unable to use Python notebooks or execute code in VS Code, blocking development work.

Request: Assistance in resolving the kernel detection issue so that VS Code can function normally.

1 answer

Your answer

Answer 1

Adiba Khan 895 Microsoft External Staff

Thanks for reaching out. Here’s some effective solutions for the VS Code issue “Stuck on Detecting Kernel”:

1**.** Verify Python and Jupyter Installation

Run these commands in a terminal (CMD or Powershell)

                           Python --version

                           Pip show jupyter

If jupyter is not installed:

Pip install notebook jupyterlab ipykernel

Then register the Python kernel:

Python -m ipykernal install --user

2. Reinstall VS code Python & Jupyter Extensions

· Open VS Code.

· Go to Extensions (ctrl+Shift+X).

· Uninstall these extensions (if already installed):

i. Python

ii. Jupyter

· Reinstall both extensions.

· Restart VS Code.

3. Select correct interpreter manually

· Open the command palette (ctrl+Shift+P).

· Type and select “Python: Select Interpreter”.

· Choose the Python environment where Jupyter is installed.

(if you use conda, select the environment)

4. Clear old Kernal cache

Sometimes older VS code versions leave corrupted cache files.

· Close VS code.

· Delete these folders:

               o   %APPDATA%\Code\User\workspaceStorage

               o   %USERPROFILE%\.vscode

· Reopen VS Code and let it rebuild the configuration.

5. Check for conflicting extensions

Disable all other extensions temporarily

· Open command palette -> “Extensions: Disable all installed Extensions”

· Enable only Python and Jupyter

· Restart VS Code and check if the kernel loads.

6. Update Everything

Update all key components:

             Pip install --upgrade pip setuptools wheel jupyter ipykernel

Then update VS Code to latest version and restart your system.

7. Reset VS code settings(optional)

If nothing works:

· Open command palette-> ”Preferences: open Settings(JSON)”

· Remove all custom Python or Jupyter related settings

· Restart VS Code- this resets kernel detection behavior.

Reference docs:

· Python Development with Visual Studio - Visual Studio (Windows) | Microsoft Learn

· Home · microsoft/vscode-jupyter Wiki · GitHub

· Python environments in VS Code

Let me know if you need any further help with this. We'll be happy to assist.

If you find this helpful, please mark this as answered.

guru charan 10 Reputation points

2025-10-13T07:40:14.05+00:00

Adiba Khan,
Unfortunately, I followed all the options, but I’m still facing the same issue — VS Code is unable to detect the kernel. Is there an option to get live support by connecting via Teams?
Adiba Khan 895 Reputation points Microsoft External Staff

2025-10-13T10:50:50.3166667+00:00
Apologies for the inconvenience. We are only able to connect via the QA platform. Please feel free to describe the issue you're encountering here.
If above steps doesn’t work you can follow these steps also:

1.      Launch VS Code with all extensions Disabled

This helps confirm if any extension (especially Python or Jupyter) is broken after update

Code --disable-extensions

Then open a .ipynb file

If the kernel loads, one of your extensions is the culprit-usually the Python, Jupyter or Pylance extension.

Try reinstalling or rolling back those

2.      Roll back to a stable version of CS code or extensions

Recent VS code or jupyter extension updates can cause detection hangs.

Try this :

·         Uninstall the latest VS Code build.

·         Install the older stable version from: https://code.visualstudio.com/updates

·         Or roll back extensions:

o   Open command palette-> Extensions:Install another version of extension

o   Choose an earlier version of Jupyter and Python.

3.      Recreate Kernel Environment from scratch

Your environment might be corrupted. Create a clean one.

For conda:

Conda create –n vscpython python=3.11 Conda activate vscpython Pip install jupyter ipykernel Python –m ipykernel install --user --name=.venv

Then in VS code:

Open command palette->“Select Kernel“->“VSCPython“

For venv users:

Python—m venv .venv .\.venv\Scripts\activate pip install jupyter ipykernel Python –m ipykernel install --user --name =.venv

4.      Reset VS Code Python Extension State

Corrupted extension state files can prevent kernel detection

%USERPROFILE%\AppData\Roaming\Code\User\globalStorage\ms-toolsai.jupyter %USERPROFILE%\AppData\Roaming\Code\User\globalStorage\ms-python.python

Then restart VS code- it will reinitialize extensions.

5.      Check Developer Console for errors

Open VS Code -> Help-> Toggle Developer tools -> Console Tab

If you see red errors like:

Failed to start kernel : Error: KernelConnectionMetadata was undefined

Or

Error: Jupyter Server failed to start

Then reinstalling the Jupyter and Python extensions or re-registering the ipykernel usually resolves it.

6.      Manually start a Jupyter Server

If VS code fails to detect it automatically:

Jupyter notebook

Then copy the URL (e.g., https://localhost:8888/?token=...).

In VS Code:

·         Open command palette-> “Jupyter: specify jupyter server for connections”

·         Paste the copied URL

This bypass VS Code’s automatic kernel detection

7.      Delete old virtual environment links

If you previously removed environments but VS code still lists them:

·         Run:

Jupyter kernelspec list

·         Delete stale kernel folders(paths printed by the command):

Jupyter kernelspec remove <kernel_name>

·         Restart VS Code and reselect the new kernel.

Let me know if you need any further help with this. We'll be happy to assist.

If you find this helpful, please mark this as answered.
Adiba Khan 895 Reputation points Microsoft External Staff

2025-10-16T09:41:40.9433333+00:00

"Hope you're doing well. We're following up on the ticket. Please let us know before 22 October whether the issue persists or has been resolved, after that we'll close this thread and If the issue has been resolved, kindly mark the response as answered."
guru charan 10 Reputation points

2025-10-19T07:13:05.27+00:00

Sir, we have already tried all your suggestions, but nothing has worked. Your application should be plug-and-play, instead of us continuously encountering errors, reporting them to you, raising tickets, and then waiting several working hours for a fix. Our bosses/clients will not accept any excuses and will not wait until these issues are resolved. Therefore, I have switched to another editor and may try again with your next release, hopefully with Visual Studio Code support.

Technical Feedback (if you want to pass this to your team): I suspect the issue is with the Jupyter or Python extension. When I switch to an older version, it asks for an update, and if I update, the interpreter keeps searching endlessly.
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Adiba Khan 895 Reputation points Microsoft External Staff

2025-10-20T10:47:59.4566667+00:00

Here is the consolidated advanced set of shape to resolve the issue:

action plan: resolving “detecting kernel” hang after extension update

we will focus on stabilizing the environment by installing a specific non good version of the extension and preventing unwanted updates that appeared to be causing the kernel detection to fail.

Phase 1: rollback and prevent automatic updates

the customers report that the older version asked for an update is key. We need to install the stable older version and immediately disable its auto update feature.

1.      Uninstall current extensions:

·         open VS code.

·         Go to extension view (ctrl +shift+ x or cmd + shift +x).

·         Find the Python And Jupiter extension.

·         Click the gear icon next to each one and select uninstall.

2.      Install a specific older version:

·         in the extension view search for the Python extension (published by Microsoft).

·         Click on the extension to open its detail page.

·         Click the gear icon next to “uninstall” button and select install another version….

·         Crucially, select a version from before last updated(e.g., a version from few months prior to October 2025). That version released right before the letters stable is often a good starting point.

·         Repeat this process for the Jupyter extension.

3.      Disable auto update for these extensions

·         while on the details page for the Python extension, click the gear icon again and ensure auto update is unchecked(or toggle it to off).

·         Repeat for the Jupyter extension.

·         This prevents the “update interpreter” loop that leads to the Hang.

Phase 2: Deep cache And configuration reset

all the basic cache clear was attempted, let's ensure all remnants of the corrupted state are gone.

1.      Close VS code completely.

2.      Manually delete corrupted state files:

delete the following folders/files. Note: these paths are 4 windows. The customer must adjust for MacOS (~library/Application support/ Code/ User) or Linux (~/.config/code/User/).

·         %USERPROFILE%\AppData\Roaming\Code\User\globalStorage\ms-toolsai.jupyter

·         %USERPROFILE%\ AppData\Roaming\Code\User\globalStorage\ms-python.python

3.      clear kernel caches (repeat from previous steps for completeness):

·         %APPDATA%\Code\User\workspaceStorage

·         %USERPROFILE%.vscode (This is where the kernelspecs might be cached)

4.      Open VS code and restart the kernel:

·         open a new or existing jupyter notebook.

·         Since we reinstalled older stable extensions, the kernel should now load correctly. If it hangs again, use the developer console

(help-> dogger developer tools-> console tab) to look for a repeated error message, such as error: Jupyter server failed to start or issue related to KernelConnectionMetadata.

Phase-3 : Isolate and verify the kernel environment

if the issue persists, the problem may be a fundamental conflict between the VS code extensions expectations and the actual Python environment.

1.      Test the Python environment outside vscode:

·         Open a standard terminal (cmd or PowerShell, not the VS code terminal)

·         Activate this specific Python environment the customer is trying to use

·         run a local jupyter notebook server

·         if the notebook successfully launches in a web browser and a simple cell runs correctly, the Python environment is healthy and the issue is definitely with VS code extensions integration.

2.      If local notebook works, manually correct VS code to it:

·         keep the local Jupiter server running from the terminal.

·         In VS code open the command palette (ctrl+shift+p)

·         type and select: Jupyter: specify Jupyter server for connections.

·         Choose existing or running(this bypasses VS code’s attempt to start the server).

·         Paste the URL provided by the terminal.

If the manual connection works the problem is specifically in the extensions code responsible for starting/spawning The Jupyter server process on the customer's machine, and the permanent fix is to wait for a subsequent patch update from Microsoft. However, phase one is the highest probability fixed for immediate relief.
Adiba Khan 895 Reputation points Microsoft External Staff

2025-10-23T14:01:05.1966667+00:00

"Hope you're doing well. We're following up on the ticket. Please let us know before 29 October whether the issue persists or has been resolved, after that we'll close this thread and If the issue has been resolved, kindly mark the response as answered."

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VS Code Stuck on "Detecting Kernel" After Latest Version Installation

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