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step1: reconstruct the WebClient class

public class MyWebClient : WebClient
    {
        protected override WebRequest GetWebRequest(Uri address)
        {
            HttpWebRequest request = base.GetWebRequest(address) as HttpWebRequest;
            request.Timeout = -1;
            request.CachePolicy = new System.Net.Cache.RequestCachePolicy(System.Net.Cache.RequestCacheLevel.NoCacheNoStore);
            request.AllowWriteStreamBuffering = false;
            return request;
        }
    }

Step2: use new WebClient as the WebClient

                WebClient web = new MyWebClient();
                web.UploadFileCompleted += new UploadFileCompletedEventHandler(web_UploadFileCompleted);
                web.UploadProgressChanged += new UploadProgressChangedEventHandler(web_UploadProgressChanged);
                FileInfo fi = new FileInfo(@"D:\VirtualBox VMs\VMxp\VMxp.vdi");
                Uri uri = new Uri("http://127.0.0.1:9090/upload");
                web.UploadFileAsync(uri, fi.FullName);