couldn't send retry but the message has been sent - botframework

Question

In the bot web chat, when I type a message, the bot says "sending" first and then changes to "couldn't send, Retry". But the message is sent and I am getting the reply. How can I avoid this? Do I need to increase the message timeout? If so, where I need to set it?
This is the code snippet. I am using C# SDK where I have coded in MessageReceivedASync method
namespace Bot_Application1.Dialogs
{
public class HRBotDialog : IDialog<object>
{
public static string dialogcontext = "";
public async Task StartAsync(IDialogContext context)
{
context.Wait(MessageReceivedAsync);
}
private async Task MessageReceivedAsync(IDialogContext context, IAwaitable<IMessageActivity> argument)
{
// Get the text passed
var message = await argument;
string typedText = message.Text.ToLower();
string answer = "My Answer";
if ((typedText == "hi") || (typedText == "hello"))
{
answer = message.Text;
}
else if ((typedText == "how many personal days do i have left") || (typedText.Contains("personal days")))
{
answer = "Looks like you have 2 remaining for this year";
}
I am adding the controller code here
//[BotAuthentication]
public class MessagesController : ApiController
{
/// <summary>
/// POST: api/Messages
/// Receive a message from a user and reply to it
/// </summary>
public async Task<HttpResponseMessage> Post([FromBody]Activity activity)
{
if (activity.Type == ActivityTypes.Message)
{
await Conversation.SendAsync(activity, () => new HRBotDialog());
}
else
{
ConnectorClient connector = new ConnectorClient(new Uri(activity.ServiceUrl));
var reply = HandleSystemMessage(activity);
if (reply != null)
await connector.Conversations.ReplyToActivityAsync(reply);
}
var response = Request.CreateResponse(HttpStatusCode.OK);
return response;
}
private Activity HandleSystemMessage(Activity message)
{
if (message.Type == ActivityTypes.DeleteUserData)
{
// Implement user deletion here
// If we handle user deletion, return a real message
}
else if (message.Type == ActivityTypes.ConversationUpdate)
{
string replyMessage = string.Empty;
if (message.MembersAdded.Any(o => o.Id == message.Recipient.Id))
{
replyMessage += $"How can I help you? \n";
return message.CreateReply(replyMessage);
}
}
else if (message.Type == ActivityTypes.ContactRelationUpdate)
{
// Handle add/remove from contact lists
// Activity.From + Activity.Action represent what happened
}
else if (message.Type == ActivityTypes.Typing)
{
// Handle knowing tha the user is typing
}
else if (message.Type == ActivityTypes.Ping)
{
}
return null;
}
}

Answer 1

Please try adding the Serializable attribute to your HRBotDialog like this:
[Serializable]
public class HRBotDialog : IDialog<object>
{
//...code...
}