[Bug]: Fails to self-correct after failing to create Python venv

[Mechputer]

Checklist

• The issue exists after disabling all extensions
• The issue exists on a clean installation of webui
• The issue is caused by an extension, but I believe it is caused by a bug in the webui
• The issue exists in the current version of the webui
• The issue has not been reported before recently
• The issue has been reported before but has not been fixed yet

What happened?

The webui.sh script fails to activate the Python virtual environment, reporting "ERROR: Cannot activate python venv, aborting...". This often occurs after an initial failure due to a missing dependency like python3.10-venv. Even after installing the dependency, subsequent attempts fail.

This happens because an initial run, without the necessary python3.10-venv or if interrupted, can create an incomplete or corrupted venv directory. The webui.sh script's logic checks for an existing venv directory. If it finds one, it doesn't attempt to recreate it, assuming it's valid. However, if this existing venv is corrupted (e.g., missing the activate script), the script then fails to find the activate script, leading to the "Cannot activate python venv, aborting..." error. This creates a persistent loop where the script never fixes the broken environment.

Resolution:

Manually remove the corrupted venv directory. This forces webui.sh to treat it as a fresh run and recreate the virtual environment correctly.

Steps to resolve:

1. Ensure all necessary system dependencies (e.g., python3.10-venv) are installed.
2. Navigate to the root directory of the stable-diffusion-webui project.
3. Remove the existing virtual environment directory:

1 rm -rf venv

4. Run the webui.sh script again. It should now successfully create and activate the virtual environment.

Steps to reproduce the problem

./webui.sh

What should have happened?

It should check if you have the ability to install a venv before creating the directory, install the dependency rather than failing, and remove a corrupted one if it fails to activate.

What browsers do you use to access the UI ?

Google Chrome

Sysinfo

sysinfo-2025-07-09-04-13.json

Console logs

$ ./webui.sh 

################################################################
Install script for stable-diffusion + Web UI
Tested on Debian 11 (Bullseye), Fedora 34+ and openSUSE Leap 15.4 or newer.
################################################################

################################################################
Running on <redacted> user
################################################################

################################################################
Repo already cloned, using it as install directory
################################################################

################################################################
ERROR: Cannot activate python venv, aborting...
################################################################
$

Additional information

This is first run without Python 3.10-venv installed. After installing, it still doesn't work because of the now broken, existing, venv. The script tells you to install the dependency, but doesn't clean up the failed creation, and then fails to start, because the venv is broken.

[viking1304]

I am confused.

How did you get broken venv if you did not have python3-venv installed?

If you do not have python3-venv installed, you should see this message: ERROR: python3-venv is not installed, aborting... before even git clone was executed.

If you have python3-venv installed, after cloning the repo, script will create venv folder if it does not exist.

What you describe can only happen if empty venv folder was manually created, or if script was manually aborted during creation of a venv folder. In any other scenario, this should not happen.

I might do some minor improvements when I find some time.

Easiest would be to delete venv if it cannot be activated, before printing this message: ERROR: Cannot activate python venv, aborting... After next launch it will be recreated.

To be honest, if this was my repo I would rewrite the whole scipt from scratch. But, since I am just a user who contribute some minor patches from time to time, I will try to keep my changes to minimum.