Entity Framework: The context is being used in Cod

Question

I am developing an WPF application with EF 6 database first approach, I am have 1 project in my solutions, if i run my project this error always appear.

The context is being used in Code First mode with code that was generated from an EDMX file for either Database First or Model First development. This will not work correctly. To fix this problem do not remove the line of code that throws this exception. If you wish to use Database First or Model First, then make sure that the Entity Framework connection string is included in the app.config or web.config of the start-up project. If you are creating your own DbConnection, then make sure that it is an EntityConnection and not some other type of DbConnection, and that you pass it to one of the base DbContext constructors that take a DbConnection. To learn more about Code First, Database First, and Model First see the Entity Framework documentation here: http://go.microsoft.com/fwlink/?LinkId=394715

Answer 1

One thing you can do is... (if is Database first)

Open the .edmx[Diagram] -> right click -> "Update Model from database"

And see if the will appear the "Add", "Refresh" and "Delete" tabs.

If doesn't... probably your connection is broken and the dialog for VS creates a new connection string will appear instead. =)