The type 'System.Data.Entity.DbContext' is defined in an assembly that is not referenced.

I've got one solution - The one project is class library with .edmx data model The other is asp.net MVC Web API project.

when i start (Build) the solution I get the following exception:

Now, to resolve this issue :

I suggest you to check Allow NuGet to download missing packages during build

In this way I got resolved the issue.