在回調中嘗試獲取WebResponse的例外

Question

我正在使用HttpWebRequest傳輸文件。工作流程是這樣的：

webRequest.BeginGetRequestStream(new AsyncCallback(WriteToStreamCallback), webRequest); 

在WriteStreamToCallback：

HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState; 
Stream requestStream = webRequest.EndGetRequestStream(asynchronousResult); 

寫字節到requestStream，然後調用：在ReadHttpResponseCallback發生

webRequest.BeginGetResponse(new AsyncCallback(ReadHttpResponseCallback), webRequest); 

例外：

HttpWebRequest webRequest = (HttpWebRequest)asynchronousResult.AsyncState; 
// The next line throws a WebException 
HttpWebResponse webResponse = (HttpWebResponse)webRequest.EndGetResponse(asynchronousResult); 

唯一的例外是：

A first chance exception of type 'System.Net.WebException' occurred in System.Windows.dll
The remote server returned an error: NotFound.

可以在該應用從此一蹶不振？可能是什麼原因？它是間歇性的;這是一個時間問題？
感謝任何見解...

UPDATE：

private void ReadHttpResponseCallback(IAsyncResult asynchronousResult) 
{ 
    try 
    { 
     HttpWebRequest webRequest = (HttpWebRequest) asynchronousResult.AsyncState; 
     // The next line throws the exception 
     HttpWebResponse webResponse = (HttpWebResponse) webRequest.EndGetResponse(asynchronousResult); 

     /* SNIP */ 
    } 
    catch (WebException webEx) 
    { 
     System.Diagnostics.Debug.WriteLine(string.Format("  {0} {1}", "ReadHttpResponseCallback - WebException", webEx.Message)); 
    } 
    catch (Exception xx) 
    { 
     System.Diagnostics.Debug.WriteLine(string.Format("{0} {1}", "ReadHttpResponseCallback", xx.Message)); 
    } 
} 

Answer 1

可能已經找到這裏的解決方案：http://fearthecowboy.com/2011/09/02/fixing-webrequests-desire-to-throw-exceptions-instead-of-returning-status/