Running Python file in Conda environment opens flash terminal with transient output, unlike base environment

[Kendr1ckFu]

Type: Bug

Behaviour

When running a Python file in a Conda environment created via conda create, the execution command is split into two steps:

1. > activate.bat py312
2. > conda run --live-stream --name py312 python {python_file_path}

This maybe causes the output to appear in what seems like a separate, transient terminal (or subprocess) that flashes and closes quickly, then call the origin terminal back. As a result:

• Standard output flashes and disappears.
• Cannot see and scroll through output using the mouse wheel.
• Poor user experience compared to running in the base/global environment.

In contrast, when using the global (base) Python environment instead of conda, the command is simply:

> python.exe {python_file_path}

and the output is displayed properly within the integrated VS Code terminal, allowing full interaction (scrolling, viewing, etc.).

Expected behavior: Output should be shown directly in the VS Code integrated terminal for all environments, without spawning transient external windows.

Steps to reproduce:

1. Create a new conda environment: conda create -n py312 python=3.12
2. Activate the environment in VS Code (via Command Palette → "Python: Select Interpreter" and choose the interpreter from py312)
3. Open a simple Python file (e.g., one with print("Hello"))
4. Run the file using the "Run Python File" button (▶️) in the top-right corner or via right-click → "Run Python File in Terminal"
5. Observe that the output flashes briefly and cannot be scrolled, while the terminal shows the two-step activation and conda run command
6. Switch to the base environment's interpreter and repeat step 4 — observe that output now persists and is scrollable

--

Extension version: 2025.12.0
VS Code version: Code 1.102.3 (488a1f239235055e34e673291fb8d8c810886f81, 2025-07-29T03:00:23.339Z)
OS version: Windows_NT x64 10.0.19045
Modes:

• Python version (& distribution if applicable, e.g. Anaconda): 3.12.6
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): System
• Value of the python.languageServer setting: Default

User Settings

languageServer: "Pylance"

Installed Extensions

Extension Name	Extension Id	Version
black-formatter	ms-	2025.2.0
copilot	Git	1.356.1735
copilot-chat	Git	0.29.1
debugpy	ms-	2025.10.0
fn-map	che	8.5.1
js-debug	ms-	1.102.0
js-debug-companion	ms-	1.1.3
material-icon-theme	PKi	5.25.0
python	ms-	2025.12.0
sqlite-viewer	qwt	0.10.6
svn-scm	joh	2.17.0
theme-dracula	dra	2.25.1
vscode-js-profile-table	ms-	1.0.10
vscode-language-pack-zh-hans	MS-	1.102.2025071609
vscode-pylance	ms-	2025.7.1
vscode-python-envs	ms-	1.2.0

System Info

Item	Value
CPUs	13th Gen Intel(R) Core(TM) i5-13400 (16 x 2496)
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)	15.62GB (5.74GB free)
Process Argv	--crash-reporter-id 9a7680a8-1840-427c-9b3f-816755953f06
Screen Reader	no
VM	50%

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yijiwantestdri0626-t:31336930
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retrydisabled:31368125

[Kendr1ckFu]

This image demonstrates the issue when running in a Conda environment.

This image demonstrates the normal execution in the global (non-Conda) environment.

[Sunlight-zero]

I met the same problem, too. I don't think that a flash terminal is a bug, although it sometimes disturbs me. But when I try to debug a file, this really causes a bug that the python script runs before conda activate. I have proposed an issue weeks ago: microsoft/vscode-python-debugger#895

[Kendr1ckFu]

I met the same problem, too. I don't think that a flash terminal is a bug, although it sometimes disturbs me. But when I try to debug a file, this really causes a bug that the python script runs before conda activate. I have proposed an issue weeks ago: #25329

I find the combined use of these two commands confusing and logically redundant. The first step — activating the Conda environment py312 via activate.bat py312 — ensures that subsequent python commands in the current terminal will use the interpreter from this environment. However, the second command uses conda run --live-stream --name py312 python main.py to explicitly run the script in the same environment again.

The issue lies in the fact that conda run inherently spawns a new env / subprocess, re-activating the specified Conda environment within it to execute the command. Even if the environment is already active, this results in redundant activation and process isolation. Although --live-stream enables real-time streaming of stdout and stderr, making output visible, the overall approach is unnecessarily duplicative and could lead to unknown issues.

Therefore, I think should avoid mixing these two patterns: "activating first" vs. "running directly." Instead, may choose one of the following approaches based on use case:

1. Activate the environment first, then run the script

conda activate py312
python main.py

2. Run directly without visible activation

conda run --live-stream --name py312 python main.py

[patrick-csliu]

I’m facing the same issue.

When I click "Run Python File", VS Code executes the following in my default terminal:

C:\Users\user\anaconda3\Scripts\activate.bat base
conda run --live-stream --name base python d:/my/python/script.py

Previously, it would directly run with:

C:\Users\user\anaconda3\python.exe d:/my/python/script.py

This happens exactly like the @Kendr1ckFu record

[patrick-csliu]

Seems is same issue, microsoft/vscode#257411

[Kendr1ckFu]

I’m facing the same issue.

When I click "Run Python File", VS Code executes the following in my default terminal:

C:\Users\user\anaconda3\Scripts\activate.bat base
conda run --live-stream --name base python d:/my/python/script.py

Previously, it would directly run with:

C:\Users\user\anaconda3\python.exe d:/my/python/script.py

This happens exactly like the @Kendr1ckFu record

Well, I believe using conda run --live-stream -name py12 python main.py is inappropriate in this scenario.
At the very least, I hope there can be an option to choose the execution method.

[albertino87]

Yes, and if in the python file there's an input() command it crashes

[anthonykim1]

I believe microsoft/vscode-python-environments#713 would close this