The Entity Framework 4.1 Update announced in July contained a bug that affected third party EF providers using a generic class for their provider factory implementation. A FileLoadException occurred with the message “The given assembly name or codebase was invalid”. Microsoft recently announced EF 4.2 Beta 1 which fixes this bug.
To refresh your memory, with EF 4.1 Update 1 there’s no need to specify ‘Persist Security Info=True’ in the connection string when using SQL authentication for Code First development. New types DbContextInfo and IDbContextFactory<TContext> have been added to make it easier to interact with DbContexts.
You can download this update using the EntityFramework.Preview package.
If you are interested in developing data apps using Entity Framework, make sure you read my article series Learn ADO.NET Entity Framework 4 – Free Tutorials