I'm having trouble getting EF 4.1 working on my computer. It seems to be some problem with my database settings. I was trying out this simple walkthrough: http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-code-first-walkthrough.aspx
But when it reaches db.Categories.Add(food); it just freeze.
I have a normal SQL Server 2008 R2 installed, not SQL Express. There also seems to be some problems with creating .mdf files instead of a direct connection to the localhost SQL server.
I've also tried adding an entity model with a database connection, but this does not seem to work. Do anyone have any pointers for me.
Thanks for any answers :)
edit: I now get a System.Data.ProviderIncompatibleException with "Vendor returned no ProviderMaifestToken-string"
I guess this is because Database Re-Initialization. If your EF code try to drop and create database with SQL Management Studion open or connected. This situation comes up.
I found the problem. These tutorials do not contain information about some vital adjustments that I needed to make it work.
1) Your application must have an App.config containing a connectionstring named with the same name as your class that inherited from DbContext. In my case "TestEF_CF.ProductContext".
2) The database cannot be created before you start to use it. Just set the Initial Catalogue to the name you want Entity Framework to create when it autocreate the database.
Once I did this, it worked properly. I got further with the first step, but got an exception when I tried to save to the database. When EF autocreated the database everything worked fine.
One thing that may have made it more problematic on my development environment could be the fact that I cannot use local mdf files directly. Still it would not hurt if the EF team could share these details more open than they do now, it would save me (or us) some frustration.
Try setting the datasource on the connection string to .\SQLEXPRESS
It did work for me
来源：https://stackoverflow.com/questions/6686693/entity-framework-4-1-code-first-freeze