@julienlg
osTicket 1.14.x is max PHP 7.2 but latest 1.115.x is max PHP 7.4. We will eventually add PHP 8 support. At this time we are focusing on the full codebase rewrite (v2.0) so updates to legacy codebase is kind of slow. You are more than welcome to submit pull request to speed up this process. If not you’ll just have to wait for us to get to it.
Cheers.