My guesses are:1. you are running nginx which is not a supported webserver for osTicket at this time. Fix 1: switch to Apache. Fix 2: go to github.com/osTicket/ read the many issue report nginx threads and re-configure your nginx to work that way it needs to.2. that SELinux or mod_security are preventing the server from doing what it is supposed to do.You can test this by disabling them. (make sure you re-enable them afterwards!!! and that you write custom rules for them to make things work.)