I'm using Unity 4 (through NuGet) with ASP.NET MVC 5. I've modified all my controller and business classes to receive their dependencies as interfaces through their constructors. 

The boostrapper class contains the following code:

```
public class Bootstrapper
{
    public static IUnityContainer UnityContainer { get; set; }

    public static void Initialize()
    {
        InitializeUnity();
        RegisterTypes();
    }

    private static void InitializeUnity()
    {
        UnityContainer = UnityConfig.GetConfiguredContainer();
        DependencyResolver.SetResolver(new UnityDependencyResolver(UnityContainer));
    }

    private static void RegisterTypes()
    {
        new Core.Bootstrapper().RegisterTypes(UnityContainer);
    }
}

```

The content of Core.Bootstrapper().RegisterTypes is as follows:

```
public IUnityContainer RegisterTypes(IUnityContainer container)
{
    // Register repositories
    container.RegisterType<IRepository, Repository>()
             .RegisterType<IBdeRepository, BdeRepository>()
             .RegisterType<IDocumentRepository, DocumentRepository>()
             .RegisterType<IHampRepository, HampRepository>()
             .RegisterType<IReportsRepository, ReportsRepository>()
             .RegisterType<ITransactionRepository, TransactionRepository>();

    // Register commands
    container.RegisterType<IBaseCommand, BaseCommand>()
             .RegisterType<IDailyLetterInfoUpdate, DailyLetterInfoUpdate>()
             .RegisterType<IDailyReconciliation, DailyReconciliation>()
             .RegisterType<InsertNewRows, InsertNewRows>()
             .RegisterType<IOrderDailyLM023, OrderDailyLM023>()
             .RegisterType<IOrderMonthlyLM012, OrderMonthlyLM012>()
             .RegisterType<IOrderMonthlyLM014, OrderMonthlyLM014>()
             .RegisterType<IPerformMonthlyRecastStatusUpdate, PerformMonthlyRecastStatusUpdate>()
             .RegisterType<IUpdateReissuedRecasts, UpdateReissuedRecasts>();

    // Register utility types
    container.RegisterType<ICsvExporter, CsvExporter>()
             .RegisterType<ILogger, Logger>();

    return container;
}

```

Finally, both UnityConfig.cs and UnityMvcActivator.cs remain unmodified from what they were when they were first installed by the NuGet package.

When I start my MVC application, I am confronted with the following error message:

> 
> Resolution of the dependency failed, type = "System.Web.Mvc.ITempDataProviderFactory", name = "(none)".
> 
> 
> Exception occurred while: while resolving.
> 
> 
> Exception is: InvalidOperationException - The current type, System.Web.Mvc.ITempDataProviderFactory, is an interface and cannot be constructed. Are you missing a type mapping?
> 
> 
> 

The class it mentions appears to be something internal to MVC, itself, which leads me to believe that I've either missed something in configuring Unity, or that I've whacked something in doing so. For the life of me, however, I can't figure out what it is, despite having consulted virtually every question I can find regarding the error message on StackOverflow. (None of the proposed solutions have resolved the issue so far, but it's quite likely I've missed something.)

Can anyone see something I've overlooked? What am I doing wrong?

**UPDATE:**

The exception is thrown here:

```
public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    routes.MapMvcAttributeRoutes(); // Exception thrown on this line.
}

```