Upgrade from Ubuntu 20.04 to 22.04 caused 503 error when accessing CyberPanel dashboard

The websites and the mail server seem to work fine. But I can’t access the CyberPanel dashboard. I have tried upgrading to the latest package but showed some kind of Python error a few seconds after I choose the version (latest). Please, check the screen below. Any suggestions on how to fix this?

Fixed this by installing Python3.8, python3.8-distitilus and python3.8-dev.
After that, I successfully upgraded to the latest version of Cyberpanel and the dashboard is accessible again.

What about you rebooting the server, have you tried that? Take a backup before you do.