How to create a venv with a different Python version

The recommended way by python.org

The recommended way of managing virtual environments since Python 3.5 is with the venv module within the Python Standard Library itself.

Source: https://docs.python.org/3/library/venv.html#creating-virtual-environments

That is not the same as virtualenv, which is a third party package, outside the Python Standard Library.

Source: https://pypi.org/project/virtualenv/

Dangerous to downgrade (and to upgrade)

Depending on if your system itself uses Python, it could be dangerous for system stability to change the system Python version. Your system might need exactly that version of Python. That is true with Ubuntu.

Instructions for Ubuntu

Tested on Ubuntu 20.04

Install another version of Python

Safer than downgrading or upgrading is installing other versions of Python on the same system.

For example, to install Python 3.9:

## Add the deadsnakes repository
me@mydevice:~$ sudo add-apt-repository ppa:deadsnakes/ppa

## Update package lists
me@mydevice:~$ sudo apt update

## Install Python 3.9
me@mydevice:~$ sudo apt install python3.9

Install the venv package and create a venv virtual environment

## Install the venv package for Python 3.9
me@mydevice:~$ sudo apt install python3.9-venv

## Make a folder for venv virtual environments
me@mydevice:~$ mkdir ~/.venvs

## Create a new venv virtual environment with Python 3.9 in it
me@mydevice:~$ python3.9 -m venv ~/.venvs/my-venv-name

## Activate the new venv
me@mydevice:~$ source ~/.venvs/my-venv-name/bin/activate
(my-venv-name) me@mydevice:~$

Check versions within the venv virtual environment

## Check the Python version inside the venv:
(my-venv-name) me@mydevice:~$ python -V
Python 3.9.9

## Check the Pip version inside the venv:
(my-venv-name) me@mydevice:~$ pip3 --version
pip 21.2.4 from /home/me/.venvs/my-venv-name/lib/python3.9/site-packages/pip (python 3.9)

Deactivate the venv virtual environment

(my-venv-name) me@mydevice:~$ deactivate
me@mydevice:~$

Check versions outside any virtual environments

## Check Python version:
me@mydevice:~$ python -V
Python 3.8.10

## Check the Pip version:
me@mydevice:~$ pip3 --version
pip 20.0.2 from /home/me/.venvs/my-venv-name/lib/python3.8/site-packages/pip (python 3.8)

Install more Python versions

To install more Python versions, just change the version number from 3.9 to which ever version you choose, that is available from the deadsnakes repository.

Simple and recent

Supposed that you have a different version of Python installed in your system. To check use the following command to check:

py --list

Output:

 -3.10-64 *
 -3.7-64

And you want to create a new virtual environment for python 3.7 on a 'test_env' directory. Run the following command:

py -3.7 -m venv test_env

Then activate the test_env by running the following command in Windows PowerShell:

.\test_env\Scripts\Activate.ps1

Or Linux:

source test_env/bin/activate

Check:

python --version

Output:

Python 3.7.0

I believe the best way to work with different python versions in isolation is pyenv, managing virtual environments can be done with pyenv-virtualenv.

I think this article from Real Python does a good job at explaining how to manage different Python versions as well as different virtual environments.

For posterity, with the tools mentioned above you can do the following (once the proper Python versions are installed)

pyenv virtualenv <python_version> <environment_name>

# Then activate it

pyenv local <environment_name>

Now that you've created a virtual environment in the folder, it should be picked up any time you enter the folder. Visual Studio Code should also pick it up, as per its documentation.

P.S.: The reason I think it's a good approach is because it allows you to manage Python versions, as well as environments, with a single tool. Each version is installed only once, in one place, which should help, because it reduces complexity.

You can use Anaconda:

conda create -n mypython3.8 python=3.8

For merely the sake of enough porridge in your stew.

For Windows users:

First, download Python 3.8 or any other Python version. Please do not add to the path if you have a preexisting installation of Python.

Then create a Python 3.8 venv by invoking the venv command:

Python38\python -m venv c:\path\to\myenv

If you are unsure of the path to the Python installation on your PC, you can run py -0p in a terminal session to verify. Your result will look like this:

 -V:3.12 *        C:\Users\Name\AppData\Local\Programs\Python\Python312\python.exe
 -V:3.8          C:\Users\Name\AppData\Local\Programs\Python\Python38\python.exe

Then activate your venv using:

c:\path\to\myenv\Scripts\activate.ps1

See Creating virtual environments.

You can do it by using the "virtualenv" library. It can be installed with command pip install virtualenv.

And then followed by the command virtualenv "name_of_your_environment" # No quotes

And then use the following code to activate your venv "name_of_your_environment"\Scripts\activate # NOTE: You MUST be at your directory where you created your env.

It’s for Visual Studio Code, but I prefer installing Conda and then creating env on the Conda prompt using Conda, which later you can access from Visual Studio Code too. It’s easy to activate that env from anywhere. Just type conda activate 'name_of_your_env' in the Visual Studio Code terminal.

The package manager uv, released in 2024, makes this very convenient.

It lets you use any Python version shown by the command uv python list, which it will install automatically, if required, separate from your system Python installation (in Linux under ~/.local/share/uv).

As of the current version, 0.8.6, the simplest command to just create an empty virtual environment which will use a specific Python version (for example, 3.8, which currently happens to also be the oldest supported version) is:

uv venv --python 3.8

Note that it will create an environment which does not contain some packages which are included when you use the standard library python -m venv, notably pip, since it assumes that you will use uv for package management.

If you just want to use uv for choosing the Python version, but not for package management, you can run the standard venv command, but with a specific Python version:

uv run --python 3.8 python -m venv

Or, if you plan to use the other Python version also outside the virtual environment, you can use uv python install 3.8 to create a symbolic link in your PATH (in Linux under ~/.local/bin), so that you can then use

python3.8 python -m venv

Without virtualenv, conda, third-party PPAs and without even installing Python anywhere in your system directories, completely contained in your local directory:

First, build the Python interpreter:

sudo apt install libffi-dev libbz2-dev liblzma-dev libncurses-dev

wget https://www.python.org/ftp/python/3.9.2/Python-3.9.2.tgz
tar -xvzf Python-3.9.2.tgz
cd Python-3.9.2
./configure
make
cd ..

Building Python doesn't take long.

You might need some header packages in Ubuntu to enable all Python features. The four above are what I needed for Python 3.9 to run a specific project correctly, found one-by-one by googling the error messages.

You can find other Python versions in the official Python FTP directory.

Then, use the build output to create your new venv:

./Python-3.9.2/python -m venv .
source ./bin/activate

Now if you just type python in your console, it should open a Python 3.9 console, until you run deactivate to exit the venv.

I had a similar case, and here is how I solved it with using pyenv to install different versions of the Python interpreter and venv to create a virtual environment.

Here is a workflow that you can give it a try:

Install pyenv

Here is a Arch Linux way of installing pyenv, and you can change the way you install it according to your operating system.

yay -S pyenv

Init pyenv for your shell

Do the things in the output after running the following command in your terminal. (In my case, edit the .zshrc file)

pyenv init

Install a new version of Python with pyenv install

Install the desired Python version with pyenv. I'll be installing version 3.10 you can change it according to your case.

pyenv install 3.10

Check version before the next step which is going to run shell command

python --version

Change your shell's Python version

Use pyenv shell to make your shell be set to the new version. This is not going to change your global settings of Python.

pyenv shell 3.10

Check the version (confirm it is changed when you compare with the previous check)

python --version

Create virtualenv (Python +3.6)

Go to the desired location (/path/to/your/project).

cd /path/to/your/project

Create the virtual environment in the location.

python -m venv .venv

Activate your virtual environment

source .venv/bin/activate

Confirm its version (it should be different than you global and be same with the version that you set with pyenv shell)

python --version

Close the current shell and open a new one. Then confirm global version of Python. By this way we'll make sure that our global system is not effected.

python --version

Go to the project directory

cd /path/to/your/project

Activate the venv

source .venv/bin/activate

Check the version (confirm it is different than the global version)

python --version

And you are all good!

In macOS, I've used Homebrew to install the Python interpreter, so I can invoke python with a chosen version to use and create the venv:

python3.8 -m venv venv

An easy solution to this problem is to:

1. First, install your desired version of Python from python.org

2. During the installation wizard, check the 'add to path' option at the bottom of the wizard, so that you don't manually have to add Python to the path from the environment variables

3. Go to the directory where you want to create the Python environment

4. Run the command py -0 to check which Python versions you have available

5. Then run the command py -//python version// -m venv //environment name// , for example py -3.9 -m venv env3.9, to create a virtual environment which uses your desired Python version

For venv you have to do it with

deadsnakes

For Ubuntu default repository all Python versions and latest ones are not there, so get the packages from repository and then install any version using apt:

sudo apt install python3.xx

And then while setting up the virtual environment use that Python:

python3.xx -m venv .venv