Web application crashes after deploying to azure because of WebRequestHandler

Question

I have an API that fetches data from other service. The following code works great on local IIS:

if (model.Phone[0] != '+')
        {
            model.Phone = "+" + model.Phone;
        }

        string data = Newtonsoft.Json.JsonConvert.SerializeObject(new { ID = Guid.NewGuid(), Phone = model.Phone});

        if (!string.IsNullOrEmpty(model.Email))
        {
            data = Newtonsoft.Json.JsonConvert.SerializeObject(new { ID = Guid.NewGuid(), Phone = model.Phone, Email = model.Email });
        }

        logger.Debug("GetDataFromSupplier before try");

        try
        {
            WebRequestHandler handler = new WebRequestHandler();
            X509Certificate2 certificate = GetMyX509Certificate();
            ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
            handler.ClientCertificates.Add(certificate);
            HttpClient client = new HttpClient(handler);
            var content = new StringContent(data, Encoding.UTF8, "application/json");
            var request = client.PostAsync(API_URL, content);
            var result = request.Result;
            return result;
        } catch (Exception ex)
        {
            logger.Debug($"GetDataFromSupplier in catch: {ex.Message}");
            var message = new HttpResponseMessage(HttpStatusCode.BadRequest);
            message.Content = new StringContent(ex.Message);
            return message;
        }

But after i have deployed this code to Azure the session breaks on this line of code:

WebRequestHandler handler = new WebRequestHandler();

The client application gets the 502 HTTP error. I have tried to increase the the RAM of webserver. The catch block not even run. What can cause this problem?

Best to use a sniffer like wireshark or fiddler. Compare the http messages from the local IIS with the one that failed. Compare the headers between working and non working. The exception is being caught in another handler or is a windows 32 method and you need to get the last windows error. — jdweng, Aug 25 '17 at 21:52

score 1 · Accepted Answer · answered Aug 26 '17 at 05:04

Looking at the documentation for WebRequestHandler https://msdn.microsoft.com/en-us/library/system.net.http.webrequesthandler(v=vs.110).aspx , it may not be the best component to use here.

Perhaps, try the same with HttpClient. https://msdn.microsoft.com/en-us/library/system.net.http.httpclient(v=vs.110).aspx because, WebRequestHandler is more for desktop applications.

Since you mentioned IIS, I am guessing you are not building a desktop app.

Web application crashes after deploying to azure because of WebRequestHandler

1 Answers1