SignalR server closes connection immediately when the client connects

1

I want to use SignalR in a project to send reboot messages to devices, but I can not. So I decided to start a new solution only for testing purposes with the same results:

SocketException (0x80004005): An existing connection was forcibly closed by the remote host

I am using Visual Studio Professional 2017 with .NET 4.7.2, and these are the steps I followed:

  1. I create a new solution with ASP.NET Web App project named SignalRServer, using Indentity for authentication.
  2. I create new folder named SignalR and add new item > SignalR Hub Class (v2). I named it SignalRHub:
public class SignalRHub : Hub
{
    public void Reboot()
    {
        Clients.All.reboot();
    }
    public void Hello()
    {
        Clients.All.hello();
    }
    public override Task OnConnected()
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} connected");
        return base.OnConnected();
    }
    public override Task OnReconnected()
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} reconnected");
        return base.OnReconnected();
    }
    public override Task OnDisconnected(bool stopCalled)
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} disconnected");
        return base.OnDisconnected(stopCalled);
    }
}
  1. In Startup.cs file:
    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.MapSignalR();
            ConfigureAuth(app);
        }
    }

Server implementation is done. After that, the client:

  1. I add a new WPF project named SignalRClient.
  2. I add Microsoft.AspNet.SignalR.Client package using Nuget.
  3. I change MainWindow.xaml:
<Window x:Class="SignalRClient.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:SignalRClient"
        mc:Ignorable="d"
        Title="MainWindow" Height="300" Width="400" Loaded="Window_Loaded">
    <Grid>
        <Button VerticalAlignment="Center" HorizontalAlignment="Center" Padding="5" Content="Send message!" Click="Button_Click"/>
    </Grid>
</Window>
  1. And finally I change MainWindow.xaml.cs:
public partial class MainWindow : Window
{
    private IHubProxy signalRHubProxy;

    public MainWindow()
    {
        InitializeComponent();
    }

    private async void Window_Loaded(object sender, RoutedEventArgs e)
    {
        try
        {
            using (var hubConnection = new HubConnection("http://localhost:54475/"))
            {
                this.signalRHubProxy = hubConnection.CreateHubProxy("SignalRHub");
                this.signalRHubProxy.On("Hello", this.HelloMessageReceived);
                this.signalRHubProxy.On("Reboot", this.RebootMessageReceived);
                ServicePointManager.DefaultConnectionLimit = 10;
                await hubConnection.Start();
                Debug.WriteLine($"[CLIENT] Connected to hub");
            }
        }
        catch (Exception exception)
        {
            Debug.WriteLine($"[CLIENT] {exception.Message}");
        }
    }

    private void HelloMessageReceived()
    {
        Console.WriteLine("[CLIENT] Hello message received");
    }
    private void RebootMessageReceived()
    {
        Console.WriteLine("[CLIENT] Reboot message received");
    }

    private async void Button_Click(object sender, RoutedEventArgs e)
    {
        await this.signalRHubProxy.Invoke("Hello", new { });
    }
}

The client is done too. Now I run the web app first, and when the home page is loaded I run the WPF app (Debug > Start new instance). This is the output:

[SERVER] b3f11c77-6bfc-416a-914b-f2573f0cc42c connected
[CLIENT] Connected to hub
[SERVER] b3f11c77-6bfc-416a-914b-f2573f0cc42c disconnected
SignalRClient.exe Error: 0 : Error while closing the websocket: System.Net.WebSockets.WebSocketException (0x80004005): An internal WebSocket error occurred. Please see the innerException, if present, for more details.  ---> System.Net.Sockets.SocketException (0x80004005): An existing connection was forcibly closed by the remote host
   at System.Net.WebSockets.WebSocketConnectionStream.WebSocketConnection.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.DelegatedStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.WebSockets.WebSocketConnectionStream.<>n__1(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.WebSockets.WebSocketConnectionStream.<WriteAsync>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Net.WebSockets.WebSocketBase.<SendFrameAsync>d__48.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at System.Net.WebSockets.WebSocketBase.WebSocketOperation.<Process>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Net.WebSockets.WebSocketBase.<CloseOutputAsyncCore>d__51.MoveNext()
   at System.Net.WebSockets.WebSocketBase.ThrowIfConvertibleException(String methodName, Exception exception, CancellationToken cancellationToken, Boolean aborted)
   at System.Net.WebSockets.WebSocketBase.<CloseOutputAsyncCore>d__51.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNet.SignalR.WebSockets.WebSocketHandler.<>c.<<CloseAsync>b__13_0>d.MoveNext() in /_/src/Microsoft.AspNet.SignalR.Core/Owin/WebSockets/WebSocketHandler.cs:line 114
The thread 0x4b44 has exited with code 0 (0x0).
The thread 0x5560 has exited with code 0 (0x0).

I can see that the client connects to the server, but the connection is immediately closed. I don't know if I am forgetting a step. I stopped the firewall with the same result. Do you know how can I solve the problem?

c#
asp.net
.net
signalr
asked on Stack Overflow Mar 6, 2020 by Jon

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