I am facing a weird problem in my Visual Studio 2013 ASP.NET MVC 5 project. All of a sudden, the IntelliSense in the Controller classes of the MVC 5 project are not working
I use VS 2013 and I had the same problem.
My solution was update VS to last version. I my case Update 4.
Simply reference in project must match with assembly in GAC on computer (OS). Intellisense come from VS not from project.