Error on type WebActivatorEx.ActivationManager threw an exception …Parameter count mismatch
问题 I am getting this error after I installed Microsoft.Owin.*. Target .Net Framework:4.5.2. Web Activator: 2.2.0 I have the same setup in another project and that seems to work fine. Please help me debug or fix this. Have I have done so far:- Updated all Nuget Packages Deleted obj folder contents Ran aspnet_compiler.exe -p C:\source\Application\MyAPI -v anything -errorstack . It did give the same error, but stopped after I added WebMatrix.data. Full Error Details :- Parameter count mismatch.