EF 4.1 exception "The provider did not return a ProviderManifestToken string"

Question

I am trying to replicate an example found on MSDN. I am using ASP.NET and EF 4.1 (CTP?). I've used NuGet to install the EntityFramework package.

I am getting this error: The provider did not return a ProviderManifestToken string ... and the database is never created.

Here is my connection string:

<add name="HospitalContext"    connectionString=    "data source=.\SQLExpress;initial catalog=NewTestDB;integrated security=True;"    providerName="System.Data.SqlClient"/> 

Here is my code:

var pat = new Patient { Name = "Shane123132524356436435234" }; db.Patients.Add(pat);  var labResult = new LabResult { Result = "bad", Patient = pat };  int recordAffected = db.SaveChanges(); 

Here is my context:

public class HospitalContext : DbContext {     static HospitalContext()     {         Database.SetInitializer(new HostpitalContextInitializer());     }      public DbSet<Patient> Patients { get; set; }     public DbSet<LabResult> LabResults { get; set; } }  public class HostpitalContextInitializer :              DropCreateDatabaseIfModelChanges<HospitalContext> {     protected override void Seed(HospitalContext context)     {         context.Patients.Add(new Patient { Name = "Fred Peters" });         context.Patients.Add(new Patient { Name = "John Smith" });         context.Patients.Add(new Patient { Name = "Karen Fredricks" });     } } 

This is a fully patched SQL 2008 system, with VS 2010 SP1.

Answer 1

I was getting this error and tried a few of the earlier suggestions. Then I checked the Inner Exception and noticed I was getting a simple SQL login failure for the user. Just something else to check.

Answer 2

This can happen sometimes when you place the connection string within the app.config of the wrong project in Visual Studio.

For example, I got this problem in EF 4.1 (the released version) project + WCF Data Service project and I noticed that I didn't have a connection string specified in the Data Services Project, where it was being used.