Cannot switch to base conda environment in interactive window after latest updates

[david-cortes]

Environment data

• VS Code version: 1.109.5
• Jupyter Extension version (available under the Extensions sidebar): 2025.9.1
• Python Extension version (available under the Extensions sidebar): 2026.2.0
• OS (Windows | Mac | Linux distro) and version: Debian Linux
• Python and/or Anaconda version: conda 24.11.3 / mamba 1.5.9
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): conda
• Jupyter server running: Local

Steps to reproduce:

1. Create a conda setup with many environments.
2. Launch a new interactive jupyter window from this extension.
3. Change the python kernel to the base conda environment.

Video:

Expected behaviour

Should switch to the base environment.

Actual behaviour

Switches to the last environment in the list, regardless of what's the current environment.

It does not affect saved interactive windows that were created before the latest updates to the python extension and vscode from a few weeks ago or so - not sure which one is at fault though.

Logs

Does not produce any log in the jupyter extension logs.

Output for Jupyter in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Jupyter)

XXX

[amunger]

is this only in the interactive window? are you able to select that kernel for a notebook in VS code?

[david-cortes]

is this only in the interactive window? are you able to select that kernel for a notebook in VS code?

Also affects notebooks.

[Jiefei-Wang]

Exactly same issue here. It only affect the base environment, the other environments are fine. I'm on Windows.

[DonJayamanne]

This looks like something related to the new Python extensoin.
@Jiefei-Wang @david-cortes If you have the Python Environments extension, please can you try to uninstall that and see if it makes a difference.
Optionally can you try to revert your Python extension to last months or month before and see if that makes a diference.
We didn't make any changes in Jupyter extension, hence this must either be caused by Python extension updates or this is an issue that has always existed or other.

[david-cortes]

@DonJayamanne If downgrading the Python extension, the base conda environment doesn't even show up in the menu anymore right after uninstalling:

After restarting vscode, it shows up again, but still suffers from the same problem.

Uninstalling the python environments extension solves the problem though.

[nahanoo]

I think I have a related bug.
If I Change Python: Select Interpreter to my conda interpreter, it doesn't actually change the interpreter.
This is a bit annoying because my packages are installed in the conda environment and therefore the linting doesn't work anymore. I think it started when migrating one of the python extensions because one was put to the graveyard a couple of days ago.
Next to the selected interpreter that I can't change, which is my system installation, there is a Global label. Maybe this was implemented a bit too globally? 😜
Best,

[nickeubank]

I'm having the same issue in notebooks and interpreter, though it appears to be intermittant — sometimes it works, sometimes when I select base it actually chooses whatever the closest environment is alphabetically.

I see there's still a info-needed tag on this — what more info would be helpful?