WebSocketException (0x80004005): The remote party closed the WebSocket connection without completing the close handshake

Question

I have a Xamarin app that communicates using WebSocket. On the client side, I am referencing the ClientWebSocket.

code:

using (var client = new ClientWebSocket() { Options = { KeepAliveInterval = new TimeSpan(0,0,3,0) }})
{
    try
    {
        await client.ConnectAsync(requestUri, cancellationToken);
        do
        {
            WebSocketReceiveResult result = null;
            var buffer = new byte[ReceiveChunkSize];
            var message = new ArraySegment<byte>(buffer);
            do
            {
                result = await client.ReceiveAsync(message, cancellationToken);
                var receivedMessage = Encoding.UTF8.GetString(buffer, 0, result.Count);
                data.Append(receivedMessage);
                if (result.MessageType != WebSocketMessageType.Text)
                    break;

            } while (!result.EndOfMessage);

            TranslateData(data);
        } while (client.State == WebSocketState.Open && !cancellationToken.IsCancellationRequested);

The application keeps throwing intermittently:

 System.Net.WebSockets.WebSocketException (0x80004005): The remote
 party closed the WebSocket connection without completing the close
 handshake.

The server has a test website where it seems to function as expected. It seems the problem is on the client. The value in the client.State is Open.

Answer 1

If anybody still findes the question like me...

I had the same problem and I added this check

result = await client.ReceiveAsync(message, cancellationToken);

if (result.Count == 0) {
    break;
}

Getting zero bytes somehow also means that the server ended the connection or something went wrong...

And I added a timer around the WebSocket to do a ping -> pong type check of the connection. Of course this is only possible if you also control the server side code. On the server side this helps you, to detect dead connections.

Links that helped me were:

https://blog.stephencleary.com/2009/05/detection-of-half-open-dropped.html

https://social.msdn.microsoft.com/Forums/vstudio/en-US/77bda5ed-0d52-4305-9a20-438e69dc2cb0/c-advanced-socket-server-100-cpu-usage-after-some-time?forum=csharpgeneral

And - like aleha_84 wrote. An exception in your loop should also trigger a reconnect.