Why does Telegram bot give 502 Bad Gateway on Http request?

Question

ASP.NET

There is a telegram bot on ASP.NET with the following code:

private void Start()
        {
            using (WebApp.Start<Startup>("http://*:8080/"))
            {
                Bot.token.SetWebhookAsync("https://адрес/WebHook").Wait();
            }
        }

 public class Startup
    {
        public static void Configuration(IAppBuilder app)
        {
            var config = new HttpConfiguration();
            config.Routes.MapHttpRoute("WebHook","{controller}");
            app.UseWebApi(config);
        }
    }

 public async Task<IHttpActionResult> Post(Update update)
        {
            var message = update.Message;

            if (message.Type == MessageType.TextMessage)
            {
                if (message.Text=="/game")
                {
                    await Bot.token.SendTextMessageAsync(message.Chat.Id,"Молоток");
                }
                else
                {
                    await Bot.token.SendTextMessageAsync(message.Chat.Id, "Не молоток");
                }
            }
            return Ok();
        }

The request is sent to the server, but the bot does not respond, instead of a response, a 502 Bad Gateway error is fixed.
At the same time, exactly the same code works without errors on the console.
How to fix this problem?

Answer 1

How to fix this problem?

Attach a log.