Hello all. I was a Windows programmer but never a website/php one and have successfully used Drupal functionality for many years.
However, the charity of which I'm a member has a free account with Krystal who are very helpful - but they're not developers. We needed to upgrade our old Drupal 9 site so I deleted the old installation and installed, using a Softaculous script, a new version 11.x. It seemed to go well apart from an error re 'trusted_host_patterns' - which I managed to fix.
However, trying to access Basic Site Settings to set things like the home page produces the error "The website encountered an unexpected error. Try again later." and the log file shows "Deprecated function: preg_quote(): Passing null to parameter #1 ($str) of type string is deprecated in Drupal\Core\Path\PathMatcher->matchPath()"
The team at Krystal Hosting installed version 10.4.6 in a 'subdirectory' and that did not display the same error so I deleted the 11.x install and installed 10.4.6 using a different Softaculous script. This produced the same 'trusted_host_patterns' error and the same error when trying to access Basic Site Settings.
This is how I've ended up here posting this message. With being no PHP or Drupal developer I am at a loss to work out what is wrong and, more importantly, how to fix it. So it works in a subdirectory but not when at the actual website.
Please can anyone suggest some solution as I am at a complete loss.
Many thanks in anticipation of your help.
David