Slow virtualenv activation in terminal may cause wrong command execution and potential data loss

[Ige-kun]

Type: Bug

Behaviour

When opening a terminal, the Python virtualenv activation command (e..g source /path/to/.venv/bin/activate) is issued too late. Most of the time, I’ve already started typing another command before activation occurs. As a result, the activation command is appended to whatever I was typing, and the combined text is executed as-is. This causes the virtualenv activation to fail, and the command I was entering is also lost.

This seems potentially dangerous, because it can result in excuting commands I never intended to run. For example, if I type rm and the activation triggers right after, the executed command becomes: rm source /path/to/.venv/bin/activate. This would obviously delete the listed paths.

This appears to be the same issue described in the now-closed #15719 (2021). That issue includes a video that already demonstrates the problem well, so I haven’t recorded a new one. Here's the video from the old issue:

Peek.19-03-2021.07-50.mp4

The problem seems to be shell-agnostic: I can reproduce it in both Bash and Fish. It’s also not caused by my custom shell configuration, since it still happens when running Bash with --noprofile --norc.

Steps to reproduce:

1. Open a new internal terminal (panel or editor area)
2. Start typing a command immediately
3. Notice that your input is appended with the virtualenv command and executed together

Diagnostic data

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

2025-09-04 13:19:15.065 [info] > pyenv which python
2025-09-04 13:19:15.066 [info] cwd: .
2025-09-04 13:19:28.051 [info] Active interpreter [/home/ige/repos/pythontest]:  /home/ige/repos/pythontest/.venv/bin/python
2025-09-04 13:19:30.733 [info] Starting Pylance language server.
2025-09-04 13:19:37.000 [info] Send text to terminal: source /home/ige/repos/pythontest/.venv/bin/activate

Extension version: 2025.12.0
VS Code version: Code 1.103.1 (360a4e4fd251bfce169a4ddf857c7d25d1ad40da, 2025-08-12T16:25:40.542Z)
OS version: Linux x64 6.15.9-201.fc42.x86_64+debug
Modes:
Remote OS version: Linux x64 6.15.9-201.fc42.x86_64+debug

• Python version: 3.13.3
• Type of virtual environment used: venv
• Value of the python.languageServer setting: Default

User Settings

languageServer: "Pylance"

testing
• pytestArgs: "<placeholder>"
• pytestEnabled: true
• pytestPath: "<placeholder>"

experiments
• enabled: false
• optOutFrom: ["pythonTerminalEnvVarActivation"]

Installed Extensions

Extension Name	Extension Id	Version
Bookmarks	ale	13.5.0
cloudcode	goo	2.36.0
code-spell-checker	str	4.2.6
copilot	Git	1.364.0
copilot-chat	Git	0.30.3
debugpy	ms-	2025.10.0
even-better-toml	tam	0.21.2
geminicodeassist	goo	2.47.0
gitlab-workflow	Git	6.40.1
gitlens	eam	17.4.1
js-debug	ms-	1.102.0
markdown-all-in-one	yzh	3.6.3
python	ms-	2025.12.0
ruff	cha	2025.24.0
shellcheck	tim	0.38.3
vscode-js-profile-table	ms-	1.0.10
vscode-kubernetes-tools	ms-	1.3.26
vscode-markdownlint	Dav	0.60.0
vscode-pylance	ms-	2025.7.1
vscode-python-envs	ms-	1.2.0
vscode-yaml	red	1.18.0

System Info

Item	Value
CPUs	AMD Ryzen 7 PRO 4750U with Radeon Graphics (16 x 1409)
GPU Status	2d_canvas: enabled 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 trees_in_viz: disabled_off video_decode: enabled video_encode: disabled_software vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: disabled_off webnn: disabled_off
Load (avg)	6, 6, 5
Memory (System)	26.49GB (6.57GB free)
Process Argv	--new-window --crash-reporter-id b1a9997c-d502-48ce-9353-1ad864d1ffab
Screen Reader	no
VM	0%
DESKTOP_SESSION	gnome
XDG_CURRENT_DESKTOP	GNOME
XDG_SESSION_DESKTOP	gnome
XDG_SESSION_TYPE	wayland

Item	Value
Remote	Dev Container: zeevending-support-backend @ unix:///run/user/1000/podman/podman.sock
OS	Linux x64 6.15.9-201.fc42.x86_64+debug
CPUs	AMD Ryzen 7 PRO 4750U with Radeon Graphics (16 x 3217)
Memory (System)	26.49GB (6.56GB free)
VM	0%

A/B Experiments

vsliv368cf:30146710
vswsl492:30256859
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
996jf627:31283433
pythonrdcb7:31342333
usemplatestapi:31297334
747dc170:31275177
aj953862:31281341
nesew2to5:31336538
agentclaude:31350858
nes-set-on:31351930
testaa123cf:31335227
onetestforazureexp:31335613
6abeh943:31336334
0927b901:31350571
custommodel2t:31371781
45650338:31358607
0cj2b977:31352657
cloudbuttonc:31374191
retryenabled:31370050
todos-0:31378732
search_len_ctrl:31378778
3efgi100_wstrepl:31374188

[danielpassy]

Extra issue with that:

Sometimes I run something with run and debug
It opens a new console, insert the command but then a env activation stops the command.

launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Django Debug",
      "type": "debugpy",
      "request": "launch",
      "program": "${workspaceFolder}/manage.py",
      "args": [
        "runserver",
        "0.0.0.0:8000"
      ],
      "django": true,
      "justMyCode": false,
      "env": {
        "MANAGE_PY_PATH": "manage.py"
      },
    },
  ]
}

Results:

The debugger hangs for quite a while and then

The workaround is quite simple, bug really annoying, stop the debugger and let this shell open

[anthonykim1]

Make sure you have environment extension enabled and set python-envs.terminal.autoActivationType to shellStartup.
Try with vscode insiders https://code.visualstudio.com/insiders/ and latest pre-release of environment extension.

If you do shell startup, you dont have to rely on the order of commands being sent to terminal.

[eleanorjboyd]

Let us know if this helps at all- we are continuing to investigate slowness in the terminal and believe it might be part of the transition to the environments extension which should be fixed once we fully switch and can remove old code as well

[github-actions]

Because we have not heard back with the information we requested, we are closing this issue for now. If you are able to provide the info later on, then we will be happy to re-open this issue to pick up where we left off.

Happy Coding!

[Ige-kun]

@anthonykim1 @eleanorjboyd This is still reproducible on the latest Insiders (1.106.0-insider) and the latest Python Environments extension preview (1.11.12861008) when using the default settings.

Only when setting "python-envs.terminal.autoActivationType": "shellStartup" does the issue go away.

Version: 1.106.0-insider
Commit: bf56edffb59c43fa0de636c3aa1d548770b168b8
Date: 2025-10-13T05:02:32.230Z
Electron: 37.6.0
ElectronBuildId: 12506819
Chromium: 138.0.7204.251
Node.js: 22.19.0
V8: 13.8.258.32-electron.0
OS: Linux x64 6.16.5-200.fc42.x86_64