Hi Ivo
I have quite a few clients for who I need to upgrade to Joomla 4.  I started on one of the easier websites.  I used the Galaxy template as it best matched their existing template.
I am using the latest version of Galaxy and Gantry 5.5.15.  There are not many components on this website.  I only imported the articles from the previous website and set up all components again on the new website.
If I leave the server as PHP 7.4 it seems to work OK, however, I get the message about it being out of date.  If I upgrade the server to PHP 8.0 I get an error page with "Sorry, there was a problem we could not recover from."
If I update to PHP 8.1 the website comes back up again.  However, I am unable to make any changes to the template.  I get this error
preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated
I have a much larger website I need to work on and would love to get some advice before I start on that.
Regards
Lynda