public static string postimg(string url,string imagePath)

        {

            string ls_r = "";

           // string imagePath = @"path/to/your/image.jpg"; // 图片路径

            //string url = "http://yourserver.com/upload"; // 上传目标URL

            string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x"); // 生成一个边界字符串

            byte[] boundaryBytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

            byte[] endBoundaryBytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");

            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(url);

            webRequest.ContentType = "multipart/form-data; boundary=" + boundary;

            webRequest.Method = "POST";

            webRequest.KeepAlive = true;

            webRequest.Credentials = System.Net.CredentialCache.DefaultCredentials;

            using (Stream requestStream = webRequest.GetRequestStream())

            {

                string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";

                FileStream fileStream = new FileStream(imagePath, FileMode.Open, FileAccess.Read);

                fileStream.CopyTo(requestStream);

                byte[] formdata = System.Text.Encoding.UTF8.GetBytes(string.Format(formdataTemplate, "image", imagePath, "image/jpeg")); // 假设是JPEG格式的图片

                requestStream.Write(boundaryBytes, 0, boundaryBytes.Length); // 分隔符开始部分

                requestStream.Write(formdata, 0, formdata.Length); // 文件描述部分（这里是固定的，可以根据需要修改）

                fileStream.Seek(0, SeekOrigin.Begin); // 重置文件流位置到开始处，以便将文件内容写入请求流中

                fileStream.CopyTo(requestStream); // 文件内容写入请求流中

                requestStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length); // 分隔符结束部分

            }

            using (HttpWebResponse response = (HttpWebResponse)webRequest.GetResponse())

            {

                using (StreamReader reader = new StreamReader(response.GetResponseStream()))

                {

                    string responseString = reader.ReadToEnd(); // 获取响应内容

                   // Console.WriteLine("Response: " + responseString); // 输出响应内容或处理响应数据

                    logCOM.f_logtxt("ResponseIMG", responseString);

                    ls_r = responseString;

                }

            }

            return ls_r;

        }

返回错误47001

 {"errcode":47001,"errmsg":"data format error rid: 67a390bf-3291c620-3bc60896"}