Trevor Trevor - 1 month ago 16
C# Question

How to get error information when HttpWebRequest.GetResponse() fails

I am initiating an HttpWebRequest and then retrieving it's response. Occasionally, I get a 500 (or at least 5##) error, but no description. I have control over both endpoints and would like the receiving end to get a little bit more information. For example, I would like to pass the exception message from server to client. Is this possible using HttpWebRequest and HttpWebResponse?

Code:

try
{
HttpWebRequest webRequest = HttpWebRequest.Create(URL) as HttpWebRequest;
webRequest.Method = WebRequestMethods.Http.Get;
webRequest.Credentials = new NetworkCredential(Username, Password);
webRequest.ContentType = "application/x-www-form-urlencoded";
using(HttpWebResponse response = webRequest.GetResponse() as HttpWebResponse)
{
if(response.StatusCode == HttpStatusCode.OK)
{
// Do stuff with response.GetResponseStream();
}
}
}
catch(Exception ex)
{
ShowError(ex);
// if the server returns a 500 error than the webRequest.GetResponse() method
// throws an exception and all I get is "The remote server returned an error: (500)."
}


Any help with this would be much appreciated.

Answer

Is this possible using HttpWebRequest and HttpWebResponse?

You could have your web server simply catch and write the exception text into the body of the response, then set status code to 500. Now the client would throw an exception when it encounters a 500 error but you could read the response stream and fetch the message of the exception.

So you could catch a WebException which is what will be thrown if a non 200 status code is returned from the server and read its body:

catch (WebException ex)
{
    using (var stream = ex.Response.GetResponseStream())
    using (var reader = new StreamReader(stream))
    {
        Console.WriteLine(reader.ReadToEnd());
    }
}
catch (Exception ex)
{
    // Something more serious happened
    // like for example you don't have network access
    // we cannot talk about a server exception here as
    // the server probably was never reached
}