Error: InnerException: System.InvalidOperationException
HResult=-2146233079
Message=There was an error invoking Hub method 'Test.DetermineLength'.

public class Program
{
    static void Main(string[] args)
    {
        string url = @"http://localhost:8080/";
        using (WebApp.Start<StartUp>(url))
        {
            Console.WriteLine(string.Format("Server running at {0}", url));
            Console.ReadLine();
        }
    }
    public class StartUp
    {
        public void Configuration(IAppBuilder app)
        {
            app.UseCors(CorsOptions.AllowAll);
            app.MapSignalR();
        }
    }
    [HubName("Test")]
    public class TestHub : Hub
    {
        [Authorize]
        public void DetermineLength(string message)
        {
            Console.WriteLine(message);
            string newMessage = string.Format(@"{0} has a length of: {1}", message, message.Length);
            Clients.All.ReceiveLength(newMessage);
        }
    }
}

public class Program
{
    static void Main(string[] args)
    {
        IHubProxy _hub;
        string url = @"http://localhost:8080/";
        var connection = new HubConnection(url);
        _hub = connection.CreateHubProxy("Test");
        connection.Start().Wait();
        string line = null;
        while ((line = System.Console.ReadLine()) != null)
        {
            _hub.Invoke("DetermineLength", line).Wait();
            _hub.On("ReceiveLength", x => Console.WriteLine(x));
        }
     }
}