How to Get Error Information When Httpwebrequest.Getresponse() Fails

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

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
}

Handling Errors from HttpWebRequest.GetResponse

Try this:

Dim req As HttpWebRequest = DirectCast(WebRequest.Create(url), HttpWebRequest)
'' set up request
Try
    Using response = req.GetResponse()
        '' success in here
    End Using
Catch ex As WebException
    Console.WriteLine(ex.Status)
    If ex.Response IsNot Nothing Then
        '' can use ex.Response.Status, .StatusDescription
        If ex.Response.ContentLength <> 0 Then
            Using stream = ex.Response.GetResponseStream()
                Using reader = New StreamReader(stream)
                    Console.WriteLine(reader.ReadToEnd())
                End Using
            End Using
        End If
    End If
End Try

---

C# version

HttpWebRequest req = (HttpWebRequest) WebRequest.Create(url);
// set up request
try {
    using (var response = req.GetResponse()) {
        // success in here
        }
}
catch (WebException ex) {
    Console.WriteLine(ex.Status);
    if (ex.Response != null) {
        // can use ex.Response.Status, .StatusDescription
        if (ex.Response.ContentLength != 0) {
            using (var stream = ex.Response.GetResponseStream()) {
                using (var reader = new StreamReader(stream)) {
                    Console.WriteLine(reader.ReadToEnd());
                }
            }
        }
    }    
}

---

Here's your code, modified a bit:

Try
    'connect with zeep'
    Dim request As HttpWebRequest = CType(WebRequest.Create( _
"https://api.zeepmobile.com/messaging/2008-07-14/send_message"), HttpWebRequest)
    request.Method = "POST"
    request.ServicePoint.Expect100Continue = False

    ' set the authorization levels'
    request.Headers.Add("Authorization", "Zeep " & API_KEY & ":" & b64)
    request.ContentType = "application/x-www-form-urlencoded"
    request.ContentLength = content.Length

    ' set up and write to stream'
    Using requestStream As Stream = request.GetRequestStream()
        Using requestWriter As New StreamWriter(requestStream)
            requestWriter.Write(content)
        End Using
    End Using

    Using myWebResponse As WebResponse = request.GetResponse()
        Using myResponseStream As Stream = myWebResponse.GetResponseStream()
            Using myStreamReader As StreamReader = New StreamReader(myResponseStream)
                Return myStreamReader.ReadToEnd()
            End Using
        End Using
    End Using
Catch ex As WebException
    Console.WriteLine(ex.Status)
    If ex.Response IsNot Nothing Then
        '' can use ex.Response.Status, .StatusDescription
        If ex.Response.ContentLength <> 0 Then
            Using stream = ex.Response.GetResponseStream()
                Using reader = New StreamReader(stream)
                    Console.WriteLine(reader.ReadToEnd())
                End Using
            End Using
        End If
    End If
End Try

---

Dumping headers:

Dim headers As WebHeaderCollection = request.Headers
' Displays the headers. Works with HttpWebResponse.Headers as well
Debug.WriteLine(headers.ToString())

' And so does this
For Each hdr As String In headers
    Dim headerMessage As String = String.Format("{0}: {1}", hdr, headers(hdr))
    Debug.WriteLine(headerMessage)
Next

How do I read a custom error message returned when HttpWebRequest.GetResponse throws a WebException?

Here's a pared-down example which reads your custom message. Your message is returned in the response stream.

try
{
    var response = request.GetResponse() as HttpWebResponse;
}
catch (WebException ex) // this exception is thrown because of the 401.
{
    var responseStream = ex.Response.GetResponseStream();
    using (var reader = new StreamReader(responseStream))
    {
        var message = reader.ReadToEnd();
    }
}

.Net HttpWebRequest.GetResponse() raises exception when http status code 400 (bad request) is returned

It would be nice if there were some way of turning off "throw on non-success code" but if you catch WebException you can at least use the response:

using System;
using System.IO;
using System.Web;
using System.Net;

public class Test
{
    static void Main()
    {
        WebRequest request = WebRequest.Create("http://csharpindepth.com/asd");
        try
        {
            using (WebResponse response = request.GetResponse())
            {
                Console.WriteLine("Won't get here");
            }
        }
        catch (WebException e)
        {
            using (WebResponse response = e.Response)
            {
                HttpWebResponse httpResponse = (HttpWebResponse) response;
                Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
                using (Stream data = response.GetResponseStream())
                using (var reader = new StreamReader(data))
                {
                    string text = reader.ReadToEnd();
                    Console.WriteLine(text);
                }
            }
        }
    }
}

You might like to encapsulate the "get me a response even if it's not a success code" bit in a separate method. (I'd suggest you still throw if there isn't a response, e.g. if you couldn't connect.)

If the error response may be large (which is unusual) you may want to tweak HttpWebRequest.DefaultMaximumErrorResponseLength to make sure you get the whole error.

HttpWebRequest call to GetResponse, fails using .net 4.5 but passes using net 4.6

This is usually caused by the server using TLS v1.2. I think Net4.5 defaults to TLS v1.1, so you must add this to your code:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

Getting content from httpwebresponse exception

EDIT : Have you tried with a simple try-catch to see if you can get more details ?

try
{
    var response = (HttpWebResponse)(request.GetResponse());
}
catch(Exception ex)
{
    var response = (HttpWebResponse)ex.Response;
}

In my recherches in an answer for you, I noticed that in code there was something about encoding, that you didn't specified. Look here for exemple with such code.

var encoding = ASCIIEncoding.ASCII;
using (var reader = new System.IO.StreamReader(response.GetResponseStream(), encoding))
{
    string responseText = reader.ReadToEnd();
}

Or here, in the doc, also.

// Creates an HttpWebRequest with the specified URL. 
HttpWebRequest myHttpWebRequest = (HttpWebRequest)WebRequest.Create(url); 
// Sends the HttpWebRequest and waits for the response.         
HttpWebResponse myHttpWebResponse = (HttpWebResponse)myHttpWebRequest.GetResponse(); 
// Gets the stream associated with the response.
Stream receiveStream = myHttpWebResponse.GetResponseStream();
Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
// Pipes the stream to a higher level stream reader with the required encoding format. 
StreamReader readStream = new StreamReader( receiveStream, encode );
Console.WriteLine("\r\nResponse stream received.");

Have you tried with such ?

Make HttpWebRequest.GetResponse() return a value when the connection fails

GetResponse throws an exception when an error occurs. For example if host cannot be resolved. All you need is to catch it and do proper action after it.

In code below I handle WebException, but some other exceptions can occur during this method. So you can general Exception class instead.

public DateTime GetInternetTime()
{
    var myHttpWebRequest = (HttpWebRequest)WebRequest.Create("http://www.microsoft.com");
    myHttpWebRequest.Timeout = 5000;
    myHttpWebRequest.ReadWriteTimeout = 5000;

    try
    {
        var response = myHttpWebRequest.GetResponse();
        string todaysDates = response.Headers["date"];
        dateTime = DateTime.ParseExact(todaysDates, "ddd, dd MMM yyyy HH:mm:ss 'GMT'", CultureInfo.InvariantCulture.DateTimeFormat, DateTimeStyles.AssumeUniversal);
        connectionFailed = false;
    } catch(WebException)
    {
        connectionFailed = true;
        dateTime = DateTime.Now;
    }

    return dateTime;
}

---

Related Topics