HttpWebRequest.GetResponse: "The underlying connection was closed: An unexpected error occurred on a receive."

Question

I've written a C# Windows service (.NET Framework 3.5, C# 3.0) that posts files & HTML form information to a remote server, and then stores the XML server response in a database. Here is the main chunk of pertinent code:

    HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest;

    request.ProtocolVersion = HttpVersion.Version10;
    request.KeepAlive = false;
    request.Timeout = 600000;
    request.ReadWriteTimeout = 600000;
    request.Method = "POST";
    request.ContentType = contentType;
    request.UserAgent = userAgent;
    request.CookieContainer = new CookieContainer();
    request.ContentLength = formData.Length;

    using (Stream requestStream = request.GetRequestStream())
    {
        // Push it out there
        requestStream.Write(formData, 0, formData.Length);
        requestStream.Close();
    }

    return request.GetResponse() as HttpWebResponse;

My service works properly for all small files, but I get the following error when I try to send larger files (8-9 MB).

    The underlying connection was closed: An unexpected error occurred on a receive.

I looked at the outgoing request using Fiddler, and was able to glean the following info:

    HTTP/1.1 504 Fiddler - Receive Failure
    Content-Type: text/html
    Connection: close
    Timestamp: 12:25:04.067

    ReadResponse() failed: The server did not return a response for this request.

The failure occurs ~7 minutes after I call request.GetResponse(). Is there any way to identify who shut down the connection? And is there anything else I should try on my end to resolve this issue? Thanks in advance!

Answer 1

Since you mention it working for small files, but not larger, I'd suggest checking the max file upload size on the server. I believe the default is 4mb. http://support.microsoft.com/kb/295626

EDIT: Noticed the link above is somewhat out of date. Here's one for iis7: http://www.cyprich.com/2008/06/19/fixing-file-upload-size-limit-in-iis-7/