This seems to be an old issue, but I'm now experiencing this in IIS 8.5:
errormessage Login.aspx not found
Tried some of the old work-arounds, but I guess this is a new issue with similar symptoms? It may be connected to running .NET 4.7.2?
When we run the app on Azure it works fine.
The app does seem to find WindowsLogin.aspx which is normal, but the redirect after that seems to go amiss.
Could have something to do with .NET 4.7.2
Any ideas?