I am getting the exception above when I run an application. The application is using asp.net mvc 3 / C#. I made an mdf file and added it under App_Data folder in Visual Web
What you really want to do to fix this is in you Context class you should have a method called OnModelCreating... make sure it has this:
Context class
OnModelCreating
protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Conventions.Remove(); }