EntityFramework-Effort: EffortProviderServices doesn't inherit from 'System.Data.Entity.Core.Common.DbProviderServices'

I get a System.InvalidOperationException on the second line:

    var connection = DbConnectionFactory.CreatePersistent(Guid.NewGuid().ToString());
    ApplicationDbContext db = new ApplicationDbContext(connection);

It happens inside the Microsoft.AspNet.Identity.EntityFramework.IdentityDbContext<ApplicationUser>.ctor I’m deriving from:

    public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
    {
        public ApplicationDbContext(DbConnection connection) : base(connection, false)
        {
        }
    }

Here’s the complete exception

System.InvalidOperationException occurred
  HResult=-2146233079
  Message=The 'Instance' member of the Entity Framework provider type 'Effort.Provider.EffortProviderServices, Effort, Version=1.0.0.0, Culture=neutral, PublicKeyToken=6a46696d54971e6d' did not return an object that inherits from 'System.Data.Entity.Core.Common.DbProviderServices'. Entity Framework providers must inherit from this class and the 'Instance' member must return the singleton instance of the provider. This may be because the provider does not support Entity Framework 6 or later; see http://go.microsoft.com/fwlink/?LinkId=260882 for more information.
  Source=EntityFramework
  StackTrace:
       at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(Type providerType)
       at System.Data.Entity.Internal.AppConfig.<.ctor>b__2(ProviderElement e)
       at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at System.Lazy`1.CreateValue()
       at System.Lazy`1.LazyInitValue()
       at System.Data.Entity.Infrastructure.DependencyResolution.AppConfigDependencyResolver.RegisterDbProviderServices()
       at System.Data.Entity.Infrastructure.DependencyResolution.AppConfigDependencyResolver.GetServiceFactory(Type type, String name)
       at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
       at System.Data.Entity.Infrastructure.DependencyResolution.AppConfigDependencyResolver.GetService(Type type, Object key)
       at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
       at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
       at System.Data.Entity.Infrastructure.DependencyResolution.CompositeResolver`2.GetService(Type type, Object key)
       at System.Data.Entity.Infrastructure.DependencyResolution.DbDependencyResolverExtensions.GetService[T](IDbDependencyResolver resolver)
       at System.Data.Entity.DbContext.InitializeLazyInternalContext(IInternalConnection internalConnection, DbCompiledModel model)
       at Microsoft.AspNet.Identity.EntityFramework.IdentityDbContext`1..ctor(DbConnection existingConnection, Boolean contextOwnsConnection)
       at MyProject.ApplicationDbContext..ctor(DbConnection connection) in ..\MyProject\ApplicationDbContext.cs:Zeile 16.
  InnerException: 

I tried to fix the App.config but it didn’t help

    <?xml version="1.0" encoding="utf-8"?>
    <configuration>
      <configSections>
        <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
        <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
      </configSections>
      <entityFramework>
        <providers>
          <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
        </providers>
      </entityFramework>
    </configuration>