How do I update a Python virtual environment with `venv` to use a newer version of Python?

Question

I have recently installed Python 3.8.0 alongside Python 3.7.4.

I have some virtual environments (created using python -m venv <directory> that are based on v3.7.4. How do I update them to use v3.8.0?

Do I need to create a new virtual environment and reinstall the dependencies, scripts, etc.?

Note: There are some existing Q&A's (such as this) that deal with the older virtualenv package/tool. I'm specifically asking about the new built-in venv module, which is a standard built-in to Python since v3.3 and has some differences from virtualenv.

Possible duplicate of [How to change the python version of already existing virtualenv?](https://stackoverflow.com/questions/51915484/how-to-change-the-python-version-of-already-existing-virtualenv) — gstukelj, Oct 25 '19 at 17:16
Possible duplicate of [Can existing virtualenv be upgraded gracefully?](https://stackoverflow.com/questions/2170252/can-existing-virtualenv-be-upgraded-gracefully) — jeremycg, Oct 25 '19 at 17:17
@gst, @jeremycg - these answers deal with the older `virtualenv` module/package. I'm only interested in the newer `venv` that is now built-in, with different usage. Updated to specify. — LightCC, Oct 25 '19 at 17:23
@chepner Whether you need to or should depends on other project requirements and cannot be generically answered. — LightCC, Oct 25 '19 at 17:23

RMPR · Accepted Answer · 2020-01-11T12:28:39.810

8

I guess what you're looking for is the --upgrade parameter.

python -m venv --help
usage: venv [-h] [--system-site-packages] [--symlinks | --copies] [--clear]
            [--upgrade] [--without-pip] [--prompt PROMPT]
            ENV_DIR [ENV_DIR ...]

Creates virtual Python environments in one or more target directories.

positional arguments:
  ENV_DIR               A directory to create the environment in.

optional arguments:
  -h, --help            show this help message and exit
  --system-site-packages
                        Give the virtual environment access to the system
                        site-packages dir.
  --symlinks            Try to use symlinks rather than copies, when symlinks
                        are not the default for the platform.
  --copies              Try to use copies rather than symlinks, even when
                        symlinks are the default for the platform.
  --clear               Delete the contents of the environment directory if it
                        already exists, before environment creation.
  --upgrade             Upgrade the environment directory to use this version
                        of Python, assuming Python has been upgraded in-place.
  --without-pip         Skips installing or upgrading pip in the virtual
                        environment (pip is bootstrapped by default)
  --prompt PROMPT       Provides an alternative prompt prefix for this
                        environment.

You need to run it with the targeted python version, for example in this case:

python3.8 -m venv --upgrade <path_to_dir>

Assuming that python3.8 is the name of your python 3.8.0 executable.

edited Jan 11 '20 at 12:28

answered Oct 25 '19 at 17:19

RMPR

3,104
3
18
29

This looks correct - what is the usage though? How do I specify which version to update to (for example)? – LightCC Oct 25 '19 at 17:25
something like `python3.8 -m venv ...` – RMPR Oct 25 '19 at 17:26
Sounds great. But I have some wrong with it: F:\MyCodes\python\dtprjops>python -m venv --upgrade venv Error: [Errno 13] Permission denied: 'F:\\MyCodes\\python\\dtprjops\\venv\\Scripts\\python.exe' – Allis Gao Jun 06 '21 at 12:33
@AllisGao You need to run it in an administrator command prompt – RMPR Jun 07 '21 at 16:27
So using vscode, you would not activate the venv and then `python -m venv --upgrade .venv` – Mike Wise Nov 15 '21 at 22:37
`--upgrade-deps` is also worth doing – Mike Wise Nov 15 '21 at 22:38
2

I don't see how `--upgrade` is useful since it doesn't 'transfer' the old site-packages to the new Python version site-package directory. Thus, you still have to reinstall all the dependencies ... So what's the point? – maxschlepzig May 08 '22 at 12:27
@maxschlepzig is right. I had to manually copy the site-packages folder to the new version. Even then, some libraries gave errors: like pyzmq. I uninstalled and reinstalled them and now it is working. – sha May 10 '22 at 22:12

How do I update a Python virtual environment with `venv` to use a newer version of Python?

1 Answers1

Linked