Trying to add/remove apps ends in "Primary script unknown"

Hi everybody,

I have a problems to add, remove, disable or enable apps. I’m getting “Primary script unknown” from php-fpm when I click on the accordant button in NC, despite that everything else seems to work. It definitely worked some time ago, however it is now a bit complicated to find out what exactly caused this issue. Unfortunately, I updated PHP to version 7.x and NC to version 11 simultaneously. My configuration is running Nginx with php-fpm. I have a bunch of different other PHP web applications running on the same machine without a problem, also NC is mostly running well, however this issue is really annoying. Don’t know where to start yet, does anybody else here have something similar?