[fsrmw_tudd]

I noticed a weird problem with the advanced search on my forum (vBulletin 4.2.5, PHP 7.027).
Whenever I'm logged in and do an advanced search for posts, the forum returns a security token missing page.
When I do the same without being logged in, I get a blank page in return.

The search for poosts is the only one affected (https://bombentrichter.de/search.php...h_type=1#ads=1)
Searching for groups or anything else doesn't return the error / blank page.

Does anyone have an idea how that can be fixed?