title: Uncaught (in promise) Error: Failed to invoke 'XXXXX' due to an error on the server
body: <p>I created a .net core chat application using SignalR and I used WebRTC for video calls. As I need to send the SDP to the receiver using server method so I created a hub method call "SendOffer". When I click Video call button I have invoked this "SendOffer" method. I have put the client side code below</p>
  
  <pre><code>var connection = new signalR.HubConnectionBuilder()
      .withUrl('/chat')
      .build();
  
  const Peer = new RTCPeerConnection();
  
  const video = document.querySelector('video');
  
  const constraints = {
      'video': true,
      'audio': true
  }
  
  document.getElementById("sendVideo").addEventListener("click", function (event) {
  
      navigator.mediaDevices.getUserMedia({
          video: true,
          audio: true,
      }).then(function (stream) {
          video.srcObject = stream
          video.play();
          //Peer.addStream(stream);
          Peer.createOffer()
              .then(sdp =&gt; Peer.setLocalDescription(sdp))
              .then(function () {
                  console.log(Peer.localDescription);
                  //connection.invoke("SendOffer", Peer.localDescription).catch(function (err) {
                  //    return console.error(err.toString());
                  connection.invoke("SendOffer", Peer.localDescription);
              })
      });
  })
  </code></pre>
  
  <p>But this gives an error in the console log and not working. blow is the error</p>
  
  <blockquote>
    <p>signalr.js:2088 Uncaught (in promise) Error: Failed to invoke
    'SendOffer' due to an error on the server.
        at _this.callbacks. (signalr.js:2088)
        at HubConnection.processIncomingData (signalr.js:2182)
        at WebSocketTransport.HubConnection.connection.onreceive (signalr.js:1905)
        at WebSocket.webSocket.onmessage (signalr.js:3949)</p>
  </blockquote>
  
  <p>Can any one please help me to solve this error.</p>