C3rd

Today, I've been developing an oDesk-like activity monitoring application but for local network for my company, Innermax Support, and I came across with a problem of an errors:

• An exception occurred during a WebClient request.
• The remote server returned an error: (417) Expectation failed.

And during my search in Google -- from forums, MSDN and other developers' resources -- they face same problem. The common issue was the 100-Continue problem passing to a network with squid-cache. So there's a websites that I combined their codes and luckily it works. Just forgot the URLs, I can't credit thank-you's to them.. hehehe! The setup is like this... there's a firewall which has squid-cache in the local network and my server where I will upload my file/image is at the other network with public IP address. I will directly upload the file/image to my server using the assigned public IP address via PHP script. Here's my code to solve the problems;

public void uploadFile()
{
    try
    {
        // decleration of webclient
        ServicePointManager.Expect100Continue = false;
        System.Net.WebClient webby = new System.Net.WebClient();

        //initiate credentials
        webby.UseDefaultCredentials = false;
        webby.Credentials = new NetworkCredential("anonymous", "");

        //add headers
        webby.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client Protocol 2.0.50727.832)");
        webby.Headers.Add("Content-Type", "binary/octet-stream");

        //initiate upload file
        Byte[] result = webby.UploadFile("http://120.0.0.1/upload.php", "POST", @filename);

        string s = System.Text.Encoding.UTF8.GetString(result, 0, result.Length);
        MessageBox.Show(s);
        webby.Dispose();
    }
    catch (Exception)
    {
        // do nothing...
        MessageBox.Show("Upload failed!");
    }
}

So far, it works fine with me and satisfied of my solution. Hope this will help your problem too... :)