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

问题

When I try my program on my win2k8 machine it runs fine but on win 2k3 it gives me this error that error message

here's the code that' generating the error

WebClient wc = new WebClient(); 
wc.DownloadFile("ftp://ftp.website.com/sample.zip");

there's the weird part. if i disable the firewall on the server completely. the error goes away. but it still errors if i add the program to the exception list and turn on the firewall.

have search the web for days, couldn't find any solution.

回答1:

You should try using passive mode for FTP. The WebClient class doesn't allow that, but FtpWebRequest does.

FtpWebRequest request = WebRequest.Create("ftp://ftp.website.com/sample.zip") as FtpWebRequest;
request.UsePassive = true;
FtpWebResponse response = request.GetResponse() as FtpWebResponse;
Stream ftpStream = response.GetResponse();
int bufferSize = 8192;
byte[] buffer = new byte[bufferSize];
using (FileStream fileStream = new FileStream("localfile.zip", FileMode.Create, FileAccess.Write))
{
    int nBytes;
    while((nBytes = ftpStream.Read(buffer, 0, bufferSize) > 0)
    {
        fileStream.Write(buffer, 0, nBytes);
    }
}

回答2:

Please post the complete exception, including any InnerException:

try
{
    WebClient wc = new WebClient(); 
    wc.DownloadFile("ftp://ftp.website.com/sample.zip");
}
catch (Exception ex)
{
    Console.WriteLine(ex.ToString()); // Or Debug.Trace, or whatever
    throw;    // As if the catch were not present
}