If you are receiving error like in title, then add in the reference :


Search for:


In my case it was in folder:

C:\Program Files (x86)\Microsoft ASP.NET\ASP.NET MVC 4\Packages\EntityFramework.5.0.0\lib\net40


Or you can do it with NuGet. Go to tools -> Library Packager Manager -> Manage NuGet Packages for Solution:

Then search for EntityFramework and install it: