Could not determine storage version - Entity Framework

Question

I'm implementing code first pattern in a separate project in my current solution. Since I did this and I initialize my connection string in DbContext I get this weird error:

Could not determine storage version; a valid storage connection or a version hint is required.

I'm using Entity Framework 5.0.0.0 and the rest of my solutions projects work great as they use EDMX files for database access yet only my code first project throws this exception. What is it and why?

Answer 1

Install EFTools6.1.3ForVS2012, mine got solved

Answer 2

Solved the same issue with:

Go to Solution Explorer

1. Right click on "xxx.edmx" file
2. Select "Open with" >> Editor XML Editor
3. Change ProviderManifestToken="XXXX" with 2008

Answer 3

It seems problem got solved when I upgraded Entity Framework for every project using it to Entity Framework 6.1.2.

Works like a charm!

Answer 4

Drop EF table __MigrationHistory, assuming you were just playing with migrations in test.