500 error without any error log entry Migrated a Drupal 8 site to another server running apache2 PHP 5.5.9 (should be supported). Apache returns 500 when index.php requested, but no errors are logged anywhere. I tested by forcing an intentional PHP error in index.php and the log contains PHP errors. 

I also excluded database connection problems. Taking settings.php out redirects me correctly to /core/install.php and no error is thrown.
If domain name is changed for new server, you need to clean cache entries. Try using truncate commands for cache tables and confirm back.
You need to have database backup before cleaning tables as well.