Python environment terminal activation breaks debugger launch

[RaphaelMelanconAtBentley]

Type: Bug

Behaviour

Launching the python debugger (from a launch config or the button in the editor) when using "python.terminal.activateEnvironment": true and a Pixi environment does not work.
The debugger server is launched, but times out because the actual python command run in the terminal is flawed:

As you can see, the command is prepended with the Pixi shell activation command and run as a whole.
The pixi shell ... command does not run code, it only activates the environment.
I believe the intended behavior is to prepent the pixi run ... command.

Steps to reproduce:

1. Create a Pixi environment.
2. Select the created environment using the "Python: Select Interpreter" command.
3. Set the "python.terminal.activateEnvironment": true setting.
4. Launch any python file for debugging.

Diagnostic data

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

2025-06-19 10:01:52.541 [info] Not enabling terminal env var experiment in multiroot remote workspaces
2025-06-19 10:01:52.544 [info] Send text to terminal: /home/pan/.pixi/bin/pixi shell --manifest-path /home/pan/repositories/Booster-AI/pixi.toml --environment booster-ai-development
2025-06-19 10:01:53.143 [info] Send text to terminal:  /usr/bin/env /home/pan/repositories/Booster-AI/.pixi/envs/booster-ai-development/bin/python /home/pan/.vscode-server/extensions/ms-python.debugpy-2025.8.0/bundled/libs/debugpy/adapter/../../debugpy/launcher 57177 -- -m deployment.scripts.build_and_push_docker_environment --environment civil_assistant_indexer --fetch-local-token --build-only --output-file ./_output/built_image.json 

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

2025-06-19 09:41:13.840 [info] Resolving launch configuration with substituted variables
2025-06-19 09:41:13.857 [info] DAP Server launched with command: /home/pan/repositories/Booster-AI/.pixi/envs/booster-ai-development/bin/python /home/pan/.vscode-server/extensions/ms-python.debugpy-2025.8.0/bundled/libs/debugpy/adapter
2025-06-19 09:41:13.959 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 09:41:13.963 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 09:41:13.963 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 09:48:22.440 [info] Resolving launch configuration with substituted variables
2025-06-19 09:48:22.454 [info] DAP Server launched with command: /home/pan/repositories/Booster-AI/.pixi/envs/booster-ai-development/bin/python /home/pan/.vscode-server/extensions/ms-python.debugpy-2025.8.0/bundled/libs/debugpy/adapter
2025-06-19 09:48:22.599 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 09:48:22.604 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 09:48:22.605 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 10:01:52.251 [info] Resolving launch configuration with substituted variables
2025-06-19 10:01:52.270 [info] DAP Server launched with command: /home/pan/repositories/Booster-AI/.pixi/envs/booster-ai-development/bin/python /home/pan/.vscode-server/extensions/ms-python.debugpy-2025.8.0/bundled/libs/debugpy/adapter
2025-06-19 10:01:52.470 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 10:01:52.473 [info] Received 'debugpySockets' event from debugpy.
2025-06-19 10:01:52.475 [info] Received 'debugpySockets' event from debugpy.

Extension version: 2025.8.0
VS Code version: Code 1.101.0 (dfaf44141ea9deb3b4096f7cd6d24e00c147a4b1, 2025-06-11T15:00:50.123Z)
OS version: Windows_NT x64 10.0.26100
Modes:
Remote OS version: Linux x64 6.6.87.2-microsoft-standard-WSL2

• Python version (& distribution if applicable, e.g. Anaconda): 3.12.11
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): Pixi
• Value of the python.languageServer setting: Pylance

User Settings

Multiroot scenario, following user settings may not apply:

languageServer: "Pylance"

testing
• cwd: "<placeholder>"
• promptToConfigure: false
• pytestArgs: "<placeholder>"
• pytestEnabled: true
• pytestPath: "<placeholder>"

experiments
• optInto: ["pythonTestAdapter"]
• optOutFrom: ["pythonTerminalEnvVarActivation"]

Installed Extensions

Extension Name	Extension Id	Version
azure-pipelines	ms-	1.249.0
copilot	Git	1.335.0
copilot-chat	Git	0.28.0
datawrangler	ms-	1.22.0
debugpy	ms-	2025.8.0
docker	doc	0.10.0
dotenv-vscode	dot	0.28.1
even-better-toml	tam	0.21.2
gitlens	eam	17.2.0
indent-rainbow	ode	8.3.1
js-debug	ms-	1.100.1
jupyter	ms-	2025.5.0
jupyter-renderers	ms-	1.1.0
markdown-all-in-one	yzh	3.6.3
markdown-preview-enhanced	shd	0.8.18
python	ms-	2025.8.0
resourcemonitor	mut	1.0.7
ruff	cha	2025.24.0
RunOnSave	eme	0.2.7
shellcheck	tim	0.37.7
tasks	act	0.16.1
vscode-ai	ms-	1.2.0
vscode-ai-remote	ms-	1.4.2
vscode-auto-open-workspace	zom	0.0.4
vscode-azureresourcegroups	ms-	0.10.13
vscode-containers	ms-	2.0.3
vscode-docker	ms-	2.0.0
vscode-js-profile-table	ms-	1.0.10
vscode-jupyter-cell-tags	ms-	0.1.9
vscode-jupyter-slideshow	ms-	0.1.6
vscode-marimo	mar	0.6.5
vscode-markdownlint	Dav	0.60.0
vscode-pylance	ms-	2025.6.1
vscode-yaml	red	1.18.0
workspace-terminals	jos	0.3.4

System Info

Item	Value
CPUs	13th Gen Intel(R) Core(TM) i7-13850HX (28 x 2304)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	31.66GB (9.34GB free)
Process Argv	--crash-reporter-id bc453f47-6475-4dca-884b-395c4b2f80af
Screen Reader	no
VM	0%

Item	Value
Remote	WSL: Ubuntu-24.04
OS	Linux x64 6.6.87.2-microsoft-standard-WSL2
CPUs	13th Gen Intel(R) Core(TM) i7-13850HX (28 x 0)
Memory (System)	15.45GB (12.42GB free)
VM	0%

A/B Experiments

vsliv368:30146709
vspor879:30202332
vspor708:30202333
vspor363:30204092
vscod805:30301674
binariesv615:30325510
vscaat:30438848
c4g48928:30535728
azure-dev_surveyonecf:30548226
962ge761:30959799
h48ei257:31000450
pythontbext0:30879054
cppperfnew:31000557
dwnewjupytercf:31046870
pythonrstrctxt:31112756
nativeloc2:31192216
5fd0e150:31155592
dwcopilot:31170013
6074i472:31201624
dwoutputs:31242946
customenabled:31248079
hdaa2157:31222309
copilot_t_ci:31222730
e5gg6876:31282496
pythoneinst12:31285622
bgtreat:31268568
4gafe986:31271826
c7cif404:31314491
pythonpulldiagcf:31325931
996jf627:31283433
pythonrdcb7:31303018
usemplatestapi:31297334
0aa6g176:31307128
7bj51361:31289155
747dc170:31275177
aj953862:31281341
generatesymbolt:31295002
convertfstringf:31295003
he899328:31327032
useunpkg:31331645
1292j425:31329156
id45c886:31329544

[anthonykim1]

Hello @RaphaelMelanconAtBentley Thanks for filing the issue.

Does it get any better if you:

1. Opt out of terminal env experiment via adding

  "python.experiments.optOutFrom": [
    "pythonTerminalEnvVarActivation"
  ],

to your settings.json?

[RaphaelMelanconAtBentley]

Hello @RaphaelMelanconAtBentley Thanks for filing the issue.

Does it get any better if you:

1. Opt out of terminal env experiment via adding

  "python.experiments.optOutFrom": [
    "pythonTerminalEnvVarActivation"
  ],

to your settings.json?

Nope, I get the exact same behavior as without it.

[RaphaelMelanconAtBentley]

I'm on WSL, but I have multiple colleagues with the same issue on MacOS.

[RaphaelMelanconAtBentley]

Here is a minimal repository that can reproduce this issue: https://github.com/RaphaelMelanconAtBentley/vscode-python-environment-activation-issue

[irm-codebase]

I am likely seeing this same problem on Fedora 42.
See here: microsoft/vscode-python-debugger#741

[RaphaelMelanconAtBentley]

Any update on this issue @anthonykim1 ? This is limiting our entire development team at the moment...

[ignition5]

I have the same problem, the solution wanted!!!