pip error in virtualenv with python 3.9 and base python 3.10

[szleb]

Issue

When creating a virtualenv with version 20.21.1 or higher with python 3.9, calling pip in the virtualenv raises the following error:

ERROR: Can not perform a '--user' install. User site-packages are not visible in this virtualenv.

The error does not appear when using python 3.10 in the virtualenv, i.e. when removing the -p py39 in the example below.

Example

>python -m virtualenv -p py39 test
created virtual environment CPython3.9.13.final.0-64 in 2877ms
  creator Venv(dest=C:\DEV\test, clear=False, no_vcs_ignore=False, global=False, describe=CPython3Windows)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=C:\Users\BEL14466\AppData\Local\pypa\virtualenv)
    added seed packages: pip==23.1, setuptools==67.6.1, wheel==0.40.0
  activators BashActivator,BatchActivator,FishActivator,NushellActivator,PowerShellActivator,PythonActivator

>test\Scripts\activate

(test)>pip install numpy
ERROR: Can not perform a '--user' install. User site-packages are not visible in this virtualenv.

[notice] A new release of pip is available: 23.1 -> 23.1.2
[notice] To update, run: python.exe -m pip install --upgrade pip

Environment

• OS: Windows 10
• base python 3.10.6
• venv python 3.9.13
• virtuelnv >= 20.21.1

system environment

>>> pip list
Package      Version
------------ -------
build        0.9.0
click        8.1.3
colorama     0.4.6
distlib      0.3.6
filelock     3.12.0
packaging    23.1
pep517       0.13.0
pip          23.1.2
pip-tools    6.13.0
platformdirs 3.4.0
setuptools   67.7.2
tomli        2.0.1
virtualenv   20.22.0
wheel        0.40.0 
 

[pfmoore]

This was an issue with pip 23.1. If you upgrade to pip 23.1.2 as the message suggests, the error will be fixed. (You may need to recreate the environment as the bug means that upgrading probably won't work 🙁)

[szleb]

Thanks for the answer @pfmoore

Indeed, if I create the environment with the following command it works.

>python -m virtualenv -p py39 --pip 23.1.2 test 

However, in real life, I actually use tox, and I do not know how I can force tox to create virtualenvs with the --pip flag.
At the moment I just set the requirement in the tox.ini to virtualenv<=20.21.0 which uses pip 23.0.1.

So at the end it is probably just a matter of time, until a new version of virtualenv uses pip 23.1.2 or higher by default.

[jugmac00]

@szleb you should be able to set the required packages and versions via https://tox.wiki/en/latest/config.html#requires

[szleb]

@jugmac00 that does not change the version wihin the testenvironments only in environment creating the virtualenvs, and changing the deps of the testinvornments requires a working pip version....