I had the same error a couple of days ago. Yesterday I was able to submit my ticket.

I guess in that situation, I'd either call my JAMF buddy or log a call via support@jamfsoftware.com.

It looks like the ticket was going through the salesforce api and the callback url after submitting the ticket was generating the 404. So the tickets were getting created, it just didn't seem like it from my end. Seems to be working now.