Ubuntu 22.04 LTS on backup server

• do-release-upgrade ran on 25/10/2022
• After quite a while, upgrade finished with positive message
• Reboot: no need to reinstall grub this time (yeah)
• Piwigo still OK under DynDNS and HTTPS (but see remark about PHP below) so mysql still OK too.   
• UrBackup server still alive and kicking after the upgrade.
  
• however : PHP was upgraded from 7.4 to 8.1 and the apache2 configuration didn't get the message so apache failed to start.  Thus:

luc@kid2:~$ sudo a2dismod php7.4
Module php7.4 disabled.
To activate the new configuration, you need to run:
  systemctl restart apache2
luc@kid2:~$ sudo a2enmod php8.1
Considering dependency mpm_prefork for php8.1:
Considering conflict mpm_event for mpm_prefork:
Considering conflict mpm_worker for mpm_prefork:
Module mpm_prefork already enabled
Considering conflict php5 for php8.1:
Enabling module php8.1.
To activate the new configuration, you need to run:
  systemctl restart apache2