Could not load file or assembly 'System.Security.Principal.Windows'

Question

Solution has compiled successfully, but after I added an existing class file to the project, this error appeared:

The specified task executable \"csc.exe\

Answer 1

I had the same issue after I upgraded Microsoft.Net.Compiler from 2.8.2 to 2.9.0. After I downgraded to 2.8.2 projects compiled without any errors.