The most common errors include:
500 Internal Server Error
- Error in .htaccess
- index.php missing
- PHP Fatal Error → see error log
403 Forbidden
- Permissions in folders
- Index file missing
- Blocked by firewall (on VPS)
404 Not Found
- Wrong route
- Files uploaded to the wrong folder
502 Bad Gateway (Nginx)
- PHP-FPM crash
- Timeout
- Wrong PHP version
