uv .venv and VS Code Jupyter Notebook: Connecting to Kernel

[wes-stone]

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Hello and thanks for all the great work with uv!

I was hoping to be able to use VS Code Jupyter notebooks with just uv to install Python. Loading the .venv works fine, but when running a code block, it is stuck in an infinite loop trying to connect to a Kernel. This only happens with VS Code Jupyter Notebooks as well. If I have the web version installed but specify to use the python installed with uv venv --python 3.10 it works fine. Would be great to not have to have a web version installed and only use uv to manage Python but understand if there's no workaround. Thanks for the help!

PS C:\Users\USER\testing stuff> uv python list
cpython-3.12.5-windows-x86_64-none     <download available>
cpython-3.11.9-windows-x86_64-none     <download available>
cpython-3.10.14-windows-x86_64-none    C:\Users\USER\AppData\Roaming\uv\data\python\cpython-3.10.14-windows-x86_64-none\python.exe
cpython-3.9.19-windows-x86_64-none     <download available>
cpython-3.8.19-windows-x86_64-none     <download available>
pypy-3.7.13-windows-x86_64-none        <download available>
PS C:\Users\wesst\testing stuff> 
 *  History restored 

Jupyter installed as well

PS C:\Users\wesst\testing stuff> uv pip tree
fqdn v1.5.1
isoduration v20.11.0
└── arrow v1.3.0
    ├── python-dateutil v2.9.0.post0
    │   └── six v1.16.0
    └── types-python-dateutil v2.9.0.20240821
jsonpointer v3.0.0
jupyter v1.0.0
├── notebook v7.2.1
.....

Visual Studio Code (1.92.2, undefined, desktop)
Jupyter Extension Version: 2024.7.0.
Python Extension Version: 2024.12.3.
Pylance Extension Version: 2024.8.2.
Platform: win32 (x64).
Workspace folder ~\testing stuff, Home = c:\Users\USER
22:17:38.461 [info] Starting Kernel (Python Path: ~\testing stuff\.venv\Scripts\python.exe, Venv, 3.10.14) for '~\testing stuff\test.ipynb' (disableUI=true)
22:17:39.048 [info] Process Execution: ~\testing stuff\.venv\Scripts\python.exe -m pip list
22:17:39.060 [info] Process Execution: ~\testing stuff\.venv\Scripts\python.exe -c "import ipykernel; print(ipykernel.__version__); print("5dc3a68c-e34e-4080-9c3e-2a532b2ccb4d"); print(ipykernel.__file__)"
22:17:39.268 [info] Process Execution: ~\testing stuff\.venv\Scripts\python.exe -c "import pip;print('6af208d0-cb9c-427f-b937-ff563e17efdf')"
22:17:39.410 [warn] No interpreter with path ~\example\.venv\Scripts\python.exe found in Python API, will convert Uri path to string as Id ~\example\.venv\Scripts\python.exe
22:17:39.458 [warn] Failed to get activated env vars for ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe in 208ms
22:17:39.460 [error] Unable to determine site packages path for python ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe (Venv)
22:17:39.471 [info] Process Execution: ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2024.7.0-win32-x64\pythonFiles\vscode_datascience_helpers\kernel_interrupt_daemon.py --ppid 14064
    > cwd: ~\.vscode\extensions\ms-toolsai.jupyter-2024.7.0-win32-x64\pythonFiles\vscode_datascience_helpers
22:17:41.868 [warn] Disposing old controller startUsingPythonInterpreter:'.jvsc74a57bd0425368e222807f297773663fdefa9d8713b24c56578a546e4a90a8565a35668f.c:\Users\~\AppData\Local\Programs\Python\Python313\python.exe.c:\Users\~\AppData\Local\Programs\Python\Python313\python.exe.-m#ipykernel_launcher' for view = 'jupyter-notebook'
22:17:41.869 [warn] Disposing old controller startUsingPythonInterpreter:'.jvsc74a57bd0425368e222807f297773663fdefa9d8713b24c56578a546e4a90a8565a35668f.c:\Users\~\AppData\Local\Programs\Python\Python313\python.exe.c:\Users\~\AppData\Local\Programs\Python\Python313\python.exe.-m#ipykernel_launcher (Interactive)' for view = 'interactive'

Below seems to be main issue.

22:17:39.458 [warn] Failed to get activated env vars for ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe in 208ms
22:17:39.460 [error] Unable to determine site packages path for python ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe (Venv)
22:17:39.471 [info] Process Execution: ~\.virtualenvs\Documents-f1-lh8zo\Scripts\python.exe c:\Users\~\.vscode\extensions\

Python scripts run fine

PS C:\Users\USER\testing stuff> uv run .\test.py   
hello uv

[zanieb]

Very weird, thanks for the report and sorry you ran into troubles here. We might need to escalate this to someone that's familiar with the Jupyter extension (cc @dhruvmanila), I have no idea why it would fail like that.

[dhruvmanila]

22:17:39.268 [info] Process Execution: ~\testing stuff\.venv\Scripts\python.exe -c "import pip;print('6af208d0-cb9c-427f-b937-ff563e17efdf')"
22:17:39.410 [warn] No interpreter with path ~\example\.venv\Scripts\python.exe found in Python API, will convert Uri path to string as Id ~\example\.venv\Scripts\python.exe

Huh, why is it looking for the interpreter in the "example" directory when the environment should be in "testing stuff" directory? How did you select the kernel in VS Code?

[dhruvmanila]

Which kernel do you see here? Can you click on it and select the current virtual environment?

[wes-stone]

Thanks for following up and yep, just the typical set up with the kernel. Actually just solved it by deleting below folder in Users\user Seems I hadn't cleaned out thoroughly Thanks again!

[dhruvmanila]

Yeah, I guess there must be some mismatch between the (old) kernel configuration and the (new) virtual environment itself.

[bjornasm]

I am not sure if it is related, but my VSCode hangs (kernel is just spinning, vscode claims it is trying to save to file) every time I add a new library using uv add and then try to import it. Have to restart vscode for it to work. I have no previous .venv in this project.

[dhruvmanila]

@wesstone12 I'm assuming that the issue is resolved on your end so closing this issue.

@bjornasm It might be unrelated. Do you mind opening a new issue with the details on how to reproduce?

[scotho3]

uv pip install ipykernel

fixed this for me. Adding for posterity

[rram12]

To explain more the solution of @scotho3, thanks Thomas btw, 1- activate your virtual environment source /path/to/venv/bin/activate 2- install the ipykernel uv pip install ipykernel 3- start vscode or jupyter server from the same command line, otherwise the kernel in question won't be selectable code .

[meehanman]

Thanks for the help! I'm able to quickly setup a new project on MacOS with VSCode via:

1. Open a fresh directory in VSCode
2. Run git init && uv init to setup the project
3. Run uv add ipykernel to add Python Notebook Tools
4. Create a new Python Notebook via touch notebook.ipynb
5. Open the Notebook in VSCode and Select Python Environments... > .venv/bin/python
6. 🕹️ Notebook is now working with uv + VSCode

I can then add additional packages via the command-line eg. uv add boto3 for AWS Tools and this will be added to my environment and pyproject.toml as well as work within my `notebook.ipynb eg:

import boto3

response = boto3.client('s3').list_objects_v2(Bucket='your-bucket-name')

---

Bonus Quickstart

mkdir notebook && cd notebook && git init && uv init && uv add ipykernel && touch notebook.ipynb