FUCKING MICROSOFT IIS SHIT.
I'm a .NET dev since 13 years and EVERY FUCKING TIME STUPID IIS MOTHERFUCKER AND STUPID WINDOWS SERVER have a different problem setting up because of some permission.
You can't never get a site up in IIS without loosing time and patience having weird 400/500.x errors because every fucking machine have to set up some tweaky and hidden permissions.
I have 2 identical fucking win servers and deploying a .NET core applications and on one works (test server) and obviously, on the production server it gives troubles.

FUCK YOU MICROSOFT FUCK YOU I would take the IIS devs personally here and whip them to death until they don't resolve the fucking thing