Blank page on View Ticket and after submission

I get a blank page after the ticket submission or if I click on the View Ticket link.
Before I update my permalinks it displayed a 404 page, after the page was blank and there is nothing to be found in the error log.

My server:
Ubuntu 14.04
HHVM 3.12.0
Redis object cache
NGINX (latest stable)

I have found the following support thread: https://www.ads-software.com/support/topic/blank-page-after-submitting-new-ticket

but there is no information about how the problem was actually solved.
Could you please elaborate me about how it was resolved?
Thank you in advance.

https://www.ads-software.com/plugins/awesome-support/