Qlik.Sense.JsonRpc.CommunicationErrorException: Connection failed after 4 attempts. Error message:
  GeneralCommunicationException with communication error WebSocketConnectionNotAccepted and http error code 500 ---> System.AggregateException: Se han producido uno o varios errores. ---> Qlik.Sense.Communication.Communication.GeneralCommunicationException: GeneralCommunicationException with communication error WebSocketConnectionNotAccepted and http error code 500
   en Qlik.Sense.Communication.Communication.WebSocketProtocol.Rfc6455Handshake.ValidateHandshakeResponse(String key, IHttpResponseHeaders response)
   en Qlik.Sense.Communication.Communication.WebSocketProtocol.Rfc6455Handshake.<>c__DisplayClass8_0.<OnHandshakeRequestWritten>b__0(IHttpResponseHeaders response)
   en Qlik.Sense.Communication.Communication.Header.HeaderParser.<>c__DisplayClass10_1.<ParseResponseHeaders>b__1()
   en Qlik.Sense.Communication.Communication.Header.HeaderParser.<>c__DisplayClass11_0.<AddHeaderValues>b__0(String line)
   en Qlik.Sense.Communication.Communication.Header.HttpHeaderLineReader.<>c__DisplayClass6_0.<ReadLine>b__1()
   en Qlik.Sense.Communication.Communication.AsyncStream.<>c__DisplayClass26_1.<ReadWhile>b__1()
   en Qlik.Sense.Communication.Communication.AsyncStream.<>c__DisplayClass26_0.<ReadWhile>b__0()
   en Qlik.Sense.Communication.ExceptionExtensions.TryCatch(Action`1 onError, Action toExec, Action`1 fatalHandling)
   --- Fin del seguimiento de la pila de la excepción interna ---
   en Qlik.Sense.JsonRpc.RpcConnection.<OpenAsync>d__43.MoveNext()
--- Fin del seguimiento de la pila de la ubicación anterior donde se produjo la excepción ---
   en System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   en System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   en Qlik.Sense.JsonRpc.RpcConnection.<EnsureConnectionIsOpen>d__54.MoveNext()
--- Fin del seguimiento de la pila de la ubicación anterior donde se produjo la excepción ---
   en System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   en System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   en Qlik.Sense.JsonRpc.RpcConnection.<SendAsync>d__52.MoveNext()
   --- Fin del seguimiento de la pila de la excepción interna ---
   en Qlik.Engine.Communication.QlikConnection.AwaitResponseTask[T](T task, String methodName, CancellationToken cancellationToken)
   en Qlik.Engine.Communication.QlikConnection.Ping(Nullable`1 noVersionCheck)
   en Qlik.Engine.LocationExtensions.Hub(ILocation location, ISession session, Nullable`1 noVersionCheck)
   en  ..MoveNext()
   en QlikView.Qvx.QvxLibrary.QvxConnection.WriteTableItemsToStream(QvxDataTable table, Stream pipeStream)
   en QlikView.Qvx.QvxLibrary.QvxConnection.InternalExecute(DataPipe dataPipe, QvxDataTable table, Action`1 onError, Action clearMExecuteError)