Fixing Python venv Installation Issue on Ubuntu 20.04 After Upgrading from Bionic

In this article, we will explore how to fix an issue that some users have experienced when trying to install Python’s venv on Ubuntu 20.04 after upgrading from Bionic. This issue often manifests as an error message suggesting that the python3-venv package cannot be installed.

Understanding the Problem

After upgrading to Ubuntu 20.04 from Bionic, you may encounter an issue when trying to create a Python virtual environment. The error message might suggest installing the python3-venv package using apt-get. However, if you have Python 3.9 installed, apt may not be able to determine the correct version to install. This can lead to conflicts and the inability to create a Python virtual environment.

Solution 1: Specifying the Full Version of python3-venv

The first solution is to explicitly specify the full version of python3-venv to install. This can be done using the following command:

sudo apt install python3.8-venv

In this command, sudo is used to run the command with root privileges, apt is the package handling utility in Ubuntu, install is the command to install a package, and python3.8-venv is the package we want to install.

After installing the package, you can recreate your virtual environment using the following command:

python3.8 -m venv env

Here, python3.8 is the version of Python we are using, -m is used to indicate that we are running a library module as a script, venv is the module we are running, and env is the name of the new virtual environment.

Solution 2: Installing python3.9-venv

If you intend to use Python 3.9, you can install the corresponding python3.9-venv package instead of python3.8-venv:

sudo apt install python3.9-venv

After installing the package, you can create a new virtual environment using the same command as in Solution 1, but replace python3.8 with python3.9.

Solution 3: Adding the focal-security Source

In some cases, the issue can be resolved by adding the focal-security source to the sources.list file. To do this, open the file /etc/apt/sources.list in a text editor with root privileges, such as nano or vim:

sudo nano /etc/apt/sources.list

Add the following line to the file:

deb http://security.ubuntu.com/ubuntu focal-security main universe

This line adds the focal-security repository to your list of package sources. The deb keyword indicates that this is a binary repository, http://security.ubuntu.com/ubuntu is the base URL of the repository, focal-security is the distribution of the repository, and main universe are the components of the repository.

Save the file and then run the following commands to update the package lists and upgrade the necessary packages:

sudo apt update
sudo apt upgrade python-pip-whl python3-pip

After completing these steps, try creating the virtual environment again.

Solution 4: Using Aptitude

Using aptitude instead of apt-get can sometimes help resolve dependency issues. First, install aptitude if it is not already installed:

sudo apt-get install aptitude

Then, use aptitude to install python3.8-venv and follow the prompts to resolve any dependency conflicts.

sudo aptitude install python3.8-venv

Once the installation is complete, you should be able to create a virtual environment using the python3 -m venv command.

Conclusion

In this article, we have explored four potential solutions to the issue of not being able to install python3-venv on Ubuntu 20.04 after upgrading from Bionic. Remember to run sudo apt update before attempting any of the solutions to ensure that you have the latest package information. If you continue to experience issues, it may be helpful to check for any conflicting PPAs or sources that may be causing the issue. Disable any extra PPAs or sources that are not necessary to avoid conflicts with package installations.