"Please note that there is currently no error in PHP error logs"That does not seem to be correct, as I see several errors, e.g.PHP Fatal error: Call to a member function getForm() on a non-object in C:\\wamp\\www\\helpdesk\\upload\\include\\class.list.php on line 561, referer: http://localhost/helpdesk/upload/open.phpI would recommend to revert things (database + osTicket installation directory) back to 1.8.1, then first upgrade to 1.8.x (latest of 1.8 branch) and switch then over to 1.9.x (1.9.8.1). Beside for me it looks like the issue is related to custom lists and forms. So what happens when you open a ticket without any custom lists and forms - just with the default fields (issue summary and issue details)?