Yea you definitely seem to be having all sorts of AJAX issues as even your system logs aren’t loading. Also, you are using an old, unsupported version of osTicket. Do you use a hosting provider or do you have your own server? If using a hosting provider it’s worth reaching out to them to see if they have any security rules, etc. that are blocking/preventing the AJAX requests. If not, then you’ll just have to look at your Apache logs to see why the AJAX requests are failing. Once you work out the AJAX issues it’s highly recommended that you upgrade to the latest (v1.18.1).
If all else fails you can just setup a new server with the latest prerequisites, install v1.18.1, run some tests to confirm AJAX is working, migrate your osTicket instance to the new server, and run the Upgrader.