No OWIN authentication manager is associated with the request

Question

After trying to enable owin & AspNet Identity to my Web Api project (in VS 2013 + .Net 4.5.1) I get the following error in each valid or unvalid(request to none exist co

Answer 1

I found the problem finally! After comparing line by line with a newly created project and finding no difference , I checked references on both projects and yes!... All the problem was from missing package :

Microsoft.Owin.Host.SystemWeb

I don't know why this packaged is missed in package installation phase but the strange point is that why didn't any build exception thrown? or no any dll reference error?