I found the error. I decided to just reinstall. When doing so, the prerequisites page told me I was missing MySQLi extension for PHP and Mbstring extension.When reverting from PHP 5.6 to 5.5 I did not select those two options.Instead of osTicket sending a 500 error, it would be nice if it took a quick look at the pre-requisites again and redirected to an error page stating that the prerequisites are missing. This would help when people are transferring from one server to another.