I was getting an Apache error on startup and during a restart after upgrading to Linux Mint 22.

As it turned out, the module that’s enabled is php8.1. It should be 8.3.

Here’s the fix:

sudo a2dismod php8.1
sudo systemctl restart apache2

This did the trick, but I was getting another error during restarting services.

The error says “could not reliably determin the server fully qualified domain.”

Here’s the fix for that.

sudo vi /etc/apache2/apache2.conf

Insert

ServerName localhost

Restart Apache

sudo systemctl restart apache2