After migrating osTicket from XAMPP on Windows to Ubuntu/Apache, clicking a ticket shows a blank detail pane

Enable Apache mod_rewrite ('a2enmod rewrite') and set AllowOverride All in the Apache VirtualHost config for the osTicket directory. Verify ost-config.php has the correct URL and database settings. Check all logs (Apache at /var/log/apache2/error.log, PHP, MySQL) and browser Developer Tools console/network tab for specific errors. Also ensure all required PHP extensions are installed (run php -m and compare to osTicket requirements). Missing extensions and incorrect .htaccess permissions are the most common causes after a platform migration.