Error starting SignalR connection: WebSocketException

[Aruljebaraj]

I tried using version 1.39 and 1.4.0. getting this error previously it was working
initializeSignalR() async {
try {

  final httpConnectionOptions = HttpConnectionOptions(
      accessTokenFactory: () => Future.value(
          'eyJ0eXAiOiJKV1QiLCJhbGciO3MiOiJQZXJtQXNzaXN0IiwiYXVkIjoiUGVybUFzc2lzdEFwcGxpY2F0aW9ucyJ9.oA6XrGUAaPmV4xsa3rnmKFJgFiZlNcAR4E_V8-e3BmE'),
      logMessageContent: true,
      skipNegotiation: true,
      transport: HttpTransportType.WebSockets);   // skipNegotiation: false throws 401,


  final hubConnection = HubConnectionBuilder()
      .withUrl(
        
          'https://notification/delivery?uniqueId=1240727',
          options: httpConnectionOptions)
      .build();
  await hubConnection.start();

  hubConnection.on(
      'SendDocumentNotificationToGroup', handleReceivedMessage);
  log('SignalR connection started.');
} catch (e) {
  log('Error starting SignalR connection: $e');
}

}

this there any solution for this?