Setup Default Python Version on Ubuntu

First, you have to check the installed Python versions on your system.

# copy the path to your python version
whereis python3.13 # replace your version with the one you want to set as default

Then, you can set the default Python version using the update-alternatives command. The higher the priority value, the higher the priority of that version.

sudo update-alternatives --install /usr/bin/python3 python3 <replace-your-path> <priority-value>
# example
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.13 1
sudo update-alternatives --config python3 # select the version you want to set as default

There are 2 choices for the alternative python3 (providing /usr/bin/python3).

  Selection    Path                       Priority   Status
------------------------------------------------------------
* 0            /usr/local/bin/python3.12   2         auto mode
  1            /usr/bin/python3.13         1         manual mode
  2            /usr/local/bin/python3.12   2         manual mode

Press <enter> to keep the current choice[*], or type selection number: 1

To check if the default Python version has been set correctly, you can run:

python3 --version

Optional: You can also set the default Python version for python command:

sudo update-alternatives --install /usr/bin/python python /usr/bin/python3.13 1
sudo update-alternatives --config python
python --version