HttpWebRequest WebException ProtocolError

Question

I'm trying to understand something about exception handling with a HttpWebRequest.

I have a client library and it's making a request to a WebAPI controller;

HttpWebRequest r = (HttpWebRequest)WebRequest.Create(url);

r.Method = "POST";
r.ContentType = "application/json";

foreach (var header in request.Headers)
{
     r.Headers.Add(header.Key, header.Value.ToString());
}

r.ContentLength = request.RequestBody.Length;

using (StreamWriter writer = new StreamWriter(r.GetRequestStream()))
    writer.Write(request.RequestBody);

I know the request will throw an exception, and contain the message entity already exists - 1234.

When I get the response;

using (HttpWebResponse response = (HttpWebResponse)r.GetResponse())
{
    if (response.StatusCode == HttpStatusCode.OK)
        using (StreamReader reader = new StreamReader(response.GetResponseStream()))
            return reader.ReadToEnd();

     return "Invalid"; 
 }

I get a WebException thrown. So, the caller of the request has a try..catch in it. And I get the WebException. What I get is a protocol error, not the 500 internal server error that was thrown (using correct status codes to represent the message comes later). Now if I read the Response of the WebException, it does contain my message and the stacktrace.

Questions

• Why do I not get a status code of 500 in my response, why does it throw a protocol error?
• Is there a more correct way of handling the request?

I have searched around and found some people getting this issue when not using the correct headers etc. But as far as I can tell, I have added all the headers that I can and still get the same behavior.

Answer 1

An 500 internal server error usually means that the API received the request but threw an unhandled exception while processing it, thus the "Internal Server Error".

You may log to a database or file all your API's unhandled exceptions to help your debugging process. Good luck.