System.Net.WebClient The underlying connection was closed - asp.net

Question

The underlying connection was closed: The connection was closed unexpectedly
I'm receiving the error message when using WebClient. I had tested this with asp code and it is running pretty well. But when I try to run the exe version of the code it running the following error, and I able to access the request address from the server, and it is within the internal network.
My server setup :-
Windows Server 2003 Entrerprise SP2
asp.net 2.0.50727
iis v6.0
Here is some code:
Manually accessing the
protected static String cross_server_req(String strContent, String strPage, String strPrivateKey)
{
try
{
WebClient wc = new WebClient();
String strURL = SERVICE_PATH + strPage + "?r=" + DES_.DESEncrypt(strContent);
byte[] responseArray = wc.DownloadData(strURL);
String strResData = Encoding.UTF8.GetString(responseArray);
if (Config.RecordWebService == "1")
{
String strLogContent = "Request:" + strContent + "\r\nResponse:" + strResData + "\r\nDateCreated:" + D_Time.DNow + "\r\n\r\n";
ServiceLog.Logger(strPage, strLogContent);
}
if (null != strResData && String.Empty != strResData)
{
return strResData.Trim();
}
}
catch (Exception ex)
{
ServiceLog.Logger("cross_server_req() Exception:" + ex.Message + "\r\n" + ex.StackTrace);
}
return null;
}
Here is from log
cross_server_req() Exception:The underlying connection was closed: The connection was closed unexpectedly.
at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request)
at System.Net.WebClient.DownloadData(Uri address)
at System.Net.WebClient.DownloadData(String address)
at Account.cross_server_request_curl(String strContent, String strPage, String strPrivateKey)
Please let me know any suggestion help this problem? I had look around the site and no solution had found.

Answer 1

I believe this error may have something to do with TLS/SSL connectivity assuming your hitting a HTTPS url. Have a look at this thread. Essentially you need to provide some code to verify that the certificate is valid. This is needed for CA's that have thumbprint issues or that aren't fully trusted. Hopefully this helps to solve your issue.
System.Net.ServicePointManager.ServerCertificateValidationCallback += new System.Net.Security.RemoteCertificateValidationCallback(validateSSLCert);
private static bool validateSSLCert(object sender, X509Certificate cert, X509Chain chain, System.Net.Security.SslPolicyErrors error)
{
return true;
}