How to configure ProviderManifestToken for EF Code First

If you're using EF 6 (just released) you have an alternative.

Dependency Resolution

You can use the new dependency resolution feature to register an implementation of IManifestTokenResolver (described in this preview documentation as IManifestTokenService).

This article gives a bit more information on how to use DbConfiguration. The easiest way to use it is like this:

DbConfigurationType(typeof(EntityFrameworkDbConfiguration))]
public class MyContextContext : DbContext
{
}

This example avoids any trip to the database when building the metadata for SQL Server connections, and automatically specifies SQL Server 2005 compatability.

using System.Data.Common;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;
using System.Data.Entity.Infrastructure.DependencyResolution;
using System.Data.SqlClient;

/// <summary>
/// A configuration class for SQL Server that specifies SQL 2005 compatability.
/// </summary>
internal sealed class EntityFrameworkDbConfiguration : DbConfiguration
{
    /// <summary>
    /// The provider manifest token to use for SQL Server.
    /// </summary>
    private const string SqlServerManifestToken = @"2005";

    /// <summary>
    /// Initializes a new instance of the <see cref="EntityFrameworkDbConfiguration"/> class.
    /// </summary>
    public EntityFrameworkDbConfiguration()
    {
        this.AddDependencyResolver(new SingletonDependencyResolver<IManifestTokenResolver>(new ManifestTokenService()));
    }

    /// <inheritdoc />
    private sealed class ManifestTokenService : IManifestTokenResolver
    {
        /// <summary>
        /// The default token resolver.
        /// </summary>
        private static readonly IManifestTokenResolver DefaultManifestTokenResolver = new DefaultManifestTokenResolver();

        /// <inheritdoc />
        public string ResolveManifestToken(DbConnection connection)
        {
            if (connection is SqlConnection)
            {
                return SqlServerManifestToken;
            }

            return DefaultManifestTokenResolver.ResolveManifestToken(connection);
        }
    }
}

After hours of searching & fiddling, I found a way to do it. Turns out the DbModelBuilder class takes a DbProviderInfo in its Build method, so I use that instead of relying on EF to call OnModelCreated:

// 'Entities' is my DbContext subclass, the "container" in EF terms.
public static Entities GetNewContext()
{
    // Get a connection, for example:
    var connection = new SqlConnection(GetConnectionString());

    // Create a DbModelBuilder
    var modelBuilder = new DbModelBuilder();
    // Configure the model builder.
    // I changed my DbContext subclass - added a public version of OnModelCreated and called it ConfigureModelBuilder
    Entities.ConfigureModelBuilder(modelBuilder);

    // Here's where the magic happens.
    // Build the model and pass the ProviderManifestToken (I use 2005 to avoid a bug in precision of sql datetime columns when using concurrency control)
    var model = modelBuilder.Build(new System.Data.Entity.Infrastructure.DbProviderInfo("System.Data.SqlClient", "2005"));
    // Compile the model
    var compiledModel = model.Compile();

    // Create the container (DbContext subclass). Ideally all the previous stuff should be cached.
    return new Entities(connection, compiledModel, true);
}

Obviously this needs some reorganization (e.g. cache the compiled model so you don't need to re-build it every time a context is created).

For me this completely solved the problem. Enjoy!

I just had this exact problem but I traced it down to my SQL Server service wasn't running. I had just restarted my computer and usually it starts on it's own but didn't for some reason.

In my case, my connection string name must match the context class name.

Connection String:

<connectionStrings>
  <add name="NunuContext" connectionString="Data Source=|DataDirectory|Nunu.sdf" providerName="System.Data.SqlServerCe.4.0" />
</connectionStrings>

Context Class:

using System.Data.Entity;
namespace Nunu.Models
{
    public class NunuContext : DbContext
    {
        System.Data.Entity.DropCreateDatabaseIfModelChanges<Nunu.Models.NunuContext>());

        public DbSet<Nunu.Models.NunuFirst> NunuFirsts { get; set; }

        public DbSet<Nunu.Models.NunuLast> NunuLasts { get; set; }
    }
}

I found, when i provided explicit "User Id=abcUser; Password=somePwd;" in my connection string i am able to resolve the same error. Earlier i was using the "Trusted_Connection=true;", which allowed me to debug my web project, but started giving me error - {"The provider did not return a ProviderManifestToken string."} as soon as i added the Windows azure project and tried debugging the Azure project after adding my web project as a web role under it.

Hope it helps some one experiencing a similar situation.

Thanks, Vivek Bahl