HttpWebRequest 、HttpWebResponse返回內容太多時，基礎連接已經關閉: 接收時發生錯誤。經過多種情況分析排查后，解決方案參考如下

                HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(new Uri(postUrl));
                webReq.Method = "POST";
                webReq.ContentType = "application/x-www-form-urlencoded";

                webReq.Accept = "*/*";
                webReq.KeepAlive = false; //重點注意此參數
                webReq.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);

                webReq.ContentLength = byteArray.Length;
                Stream newStream = webReq.GetRequestStream();
                newStream.Write(byteArray, 0, byteArray.Length);
                newStream.Close();

                HttpWebResponse response = (HttpWebResponse)webReq.GetResponse();
                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                string _Result = sr.ReadToEnd();