Probleme 1. Showing /index.php/clean_url_path
If you are activated 'Aggregate CSS files' on admin/config/development/performance, Disable it and refresh the page.
If the page display correctly, Probleme is in CSS Aggregation.
This is due to file/folder permission. so drupal cant write twig tempory files.
Change folder owner / permission like:
chown DRUPAL:www-data -R files/* (On debian/Ubuntu)
chown DRUPAL:apache -R files/* (On Redhat/CentOD/Fedors)
This is due to trusted host configuration of the serveur. It can produce when you change the domain name or 'trusted_host_patterns'. To resolve the probleme, add your new domain to the DRUPAL_ROOT/sites/SITE_FOLDER/settings.php (Ex: sites/defaults/settings.php)
As the solution depend on your error, first of all, you must find why drupal crash.
1. First thing is, You must check the serveur error log.
# tail -f /var/log/apache2/error.log
Reson 1 : FollowSymLinks
By default, virtualmin does not support
Options +FollowSymLinks (on .htaccess).
Solution 1 : Recommended