I don't know if it is the same problem that I had. I made a modification in the admin panel, in the configuration of the default SLA. Before, the setting was 4 hours, and I changed it to 72 hours. A few weeks later, the error appeared. To fix this, I changed the default SLA back to 4 hours and the ticket creation panel worked again.
the way: MANAGE → SLA → Default SLA → Change 4 hours to test.
error IMAGE:


