Redmine

Sorry, I forgot some details :

MariaDB version : 10.11.6-MariaDB-0+deb12u1
Ruby-aware server used : Webrick
Rails version : Rails 6.1.7.7
Ruby implementation and version : production ; ruby 3.1.2p20 (2022-04-12 revision 4491bb740a) [x86_64-linux-gnu]

I've found the solution to my problem.
For anyone having the same error, enter this command as root / sudo :

passenger-config --detect-apache2

You'll then see this line at the bottom:

To troubleshoot, please read the logs in this file:
/var/log/apache2/error.log


Open the Apache2 error log using :

cat /var/log/apache2/error.log

In the Apache2 error log, it is mentioned that a more recent version of the 'strscan' gem is required. You can then update it by typing the command as root / sudo :

gem install strscan (https://rubygems.org/gems/strscan/versions/3.1.0?locale=fr)

Then reload your Apache2 service and everything should work.