osTicket does not have a Docker image. There are 3rd party Docker images but they are not release by osTicket.
This type of issue we see most commonly when people are using nginx. This is not a supported webserver with osTicket at this time. We only currently support Apache and IIS. You can get nginx to work, but it will not work out of the box and you will have to peruse the nginx threads over at github to see what configuration changes that you will need to make with nginx to make it work. If you are using Apache then it seems that something like mod_rewrite is going crazy, and will need to look at your .htaccess rules, etc.
