karmakoma
You'll need to tell us more information like what webserver you are using, what your server OS is, etc. If you are using NGINX then you'll need to search online for the correct NGINX config to use. NGINX is not supported out of the box with osTicket.
Other than that you'd need to check your logs (general server logs, webserver error logs, PHP error logs, MySQL/MariaDB error logs, osTicket System Logs, Browser Console logs, etc.) for any related errors.
Cheers.
