System.AggregateException in SignalR when calling Connection.Start

Question

I have a server and client project. Each project is in it's own solution and are hosted on TFS. I am trying to make a simple SignalR program.

The client is a WPF Client, there is a opening window -> User clicks a button, is brought to a HomePage Window. This window automatically connects to the server.

public partial class HomeWindow : Window
 {
    public Player player { get; set; }
    public IHubProxy _hub { get; set; }
    string url = @"http://localhost:63346/";
    public HubConnection Connection { get; set; }


    public HomeWindow()
    {
        InitializeComponent();
        //This is a mock player. The player class should actually be generated from data pulled
        //from the database when the player authenticates
        player = new Player(150);
        Connection = new HubConnection(url);
        _hub = Connection.CreateHubProxy("MyHub");
        Connection.Start().Wait(); //Here is where the error comes from
    }

On the Connection.Start.Wait(); Line, the compiler gives the System.AggregateException. (InnerException StatusCode: 500, ReasonPhrase: 'Internal Server Error', Version: 1.1, Content: System.Net.Http.StreamContent, Headers: { Date: Sat, 29 Oct 2016 05:24:40 GMT Server: Microsoft-HTTPAPI/2.0 Content-Length: 0 })

Because the inner exception mentions error 500, here is the server info too.

[HubName("MyHub")]
class MyHub : Hub
{

}

Program.cs

    static void Main(string[] args)
    {
        string url = @"http://localhost:63346/";
        using (WebApp.Start<Startup>(url))
        {
            Console.WriteLine(string.Format("Server running at {0}", url));
            Console.ReadLine();
        }
    }

Startup.cs

class Startup
{
    public void Configuration(IAppBuilder app)
    {
        app.UseCors(CorsOptions.AllowAll);
        app.MapSignalR();
    }
}

Full exception details

System.AggregateException was unhandled
HResult=-2146233088
Message=One or more errors occurred.
Source=mscorlib
StackTrace:
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at Client.HomeWindow..ctor() in C:\Users\Zachary\Documents\Visual Studio 2015\Projects\Matchmaking Client\Client\HomeWindow.xaml.cs:line 37
   at Client.MainWindow.button_Click(Object sender, RoutedEventArgs e) in C:\Users\Zachary\Documents\Visual Studio 2015\Projects\Matchmaking Client\Client\MainWindow.xaml.cs:line 30
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs e)
   at System.Windows.Controls.Primitives.ButtonBase.OnClick()
   at System.Windows.Controls.Button.OnClick()
   at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e)
   at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
   at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e)
   at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
   at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Application.RunDispatcher(Object ignore)
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run(Window window)
   at System.Windows.Application.Run()
   at Client.App.Main()
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel)
   at System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly()
   at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData)
   at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext)
   at System.Activator.CreateInstance(ActivationContext activationContext)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()
  InnerException: 
   HResult=-2146233088
   Message=StatusCode: 500, ReasonPhrase: 'Internal Server Error', Version: 1.1, Content: System.Net.Http.StreamContent, Headers:
{
  Date: Sat, 29 Oct 2016 16:08:23 GMT
  Server: Microsoft-HTTPAPI/2.0
  Content-Length: 0
}
   Source=Microsoft.AspNet.SignalR.Client
   StackTrace:
        at Microsoft.AspNet.SignalR.Client.Http.DefaultHttpClient.<>c__DisplayClass5_0.<Get>b__1(HttpResponseMessage responseMessage)
        at Microsoft.AspNet.SignalR.TaskAsyncHelper.<>c__DisplayClass31_0`2.<Then>b__0(Task`1 t)
        at Microsoft.AspNet.SignalR.TaskAsyncHelper.TaskRunners`2.<>c__DisplayClass3_0.<RunTask>b__0(Task`1 t)
   InnerException:

Did you check the InnerExceptions collection on the AggregateException? That will give more details. — Suresh
Removing the .Wait() at the end of the Connection.Start() made the program give no errors in startup, but when trying to call Hub.Invoke() it said System.InvalidOperationException, Data cannot be sent because the connection is in a disconnected state. Call start before sending any data — Zachary Brooks
In my case, on client side of signalR desktop app, connection.CreateHubProxy("myHub") method's parameter expects exact hub name you defined in server side which is inherited from Hub class. I had a typo, fixed it and worked. — ibubi

Smug Smug · Accepted Answer · 2019-12-16T21:44:58

I got the same error and it was because the wrong URL.

I was using API URL instead main project URL where SignalR hub starts.
I was using https instead of http.

This implies, this error is a Generic error and doesn't give many details. Please have a look again on your code and recent changes.

System.AggregateException in SignalR when calling Connection.Start

1 Answers