Comment 2 for bug 2043767

Thank you for taking the time to file a bug report.

Based on DpkgTerminalLog.txt, it seems like the issue is related to the fact that some configuration files were manually removed:

Setting up php8.1-mbstring (8.1.2-1ubuntu2.14) ...
Not replacing deleted config file /etc/php/8.1/mods-available/mbstring.ini
WARNING: Module mbstring ini file doesn't exist under /etc/php/8.1/mods-available
WARNING: Module mbstring ini file doesn't exist under /etc/php/8.1/mods-available
Setting up libapache2-mod-php8.1 (8.1.2-1ubuntu2.14) ...
Not replacing deleted config file /etc/php/8.1/apache2/php.ini
Module mpm_event disabled.
Enabling module mpm_prefork.
apache2_switch_mpm Switch to prefork
dpkg: error processing package libapache2-mod-php8.1 (--configure):
 installed libapache2-mod-php8.1 package post-installation script subprocess returned error exit status 1

This seems to be causing the installation problem you're seeing, because php8.1 cannot start without its configuration files. Can you please confirm this information?

Since it seems likely to me that this is a local configuration problem,
rather than a bug in Ubuntu, I am marking this bug as 'Incomplete'.

However, if you believe that this is really a bug in Ubuntu, then we would
be grateful if you would provide a more complete description of the problem
with steps to reproduce, explain why you believe this is a bug in Ubuntu
rather than a problem specific to your system, and then change the bug
status back to "New".

For local configuration issues, you can find assistance here:
http://www.ubuntu.com/support/community