HttpWebRequest httpclient = (HttpWebRequest)WebRequest.Create("https://api.constantcontact.com/v2/activities/addcontacts?api_key=[REDACTED]");             string boundary = "--" + Guid.NewGuid().ToString();               string  filename = "F:\\constant contact Wrapper\\Constant.csv";             httpclient.Headers.Add("Authorization", "Bearer [REDACTED]");            // httpclient.Headers.Add("Accept", "application/json");             // httpclient.Headers.Add("content-type", "multipart/form-data");           // File fileToUse = new File();            // FileBody data = new FileBody(fileToUse);              httpclient.Method = "POST";         httpclient.ContentType = string.Format("multipart/form-data");         httpclient.Accept = "application/json";         httpclient.PreAuthenticate = true;            //string  filename = "C:\\Development\\constantcontact\\emailkust.csv";             StringBuilder sb= new StringBuilder();              sb.AppendLine(boundary);         sb.AppendLine("content-disposition: form-data; name="+filename  +"");         sb.AppendLine();         sb.AppendLine("Constant.csv"); //'filename         sb.AppendLine(boundary);         sb.AppendLine("content-disposition: form-data; name=" + filename + "");         //sb.AppendLine("content-disposition: form-data");//; name=""lists""");         sb.AppendLine();         sb.AppendLine("1") ;//' List Number         sb.AppendLine(boundary);         sb.AppendLine("content-disposition: form-data; name=" + filename + "");           //   sb.AppendLine("content-disposition: file");           //   sb.AppendLine("content-disposition: file; name=""data"" filename=""emailkust.csv""");         //sb.AppendLine("content-disposition: form-data; filename=Constant.csv");         sb.AppendLine("Content-Type: text/csv");         sb.AppendLine();             using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))             {                     byte[] contents = new byte[fs.Length];                     fs.Read(contents, 0, contents.Length);                     sb.Append(Encoding.Default.GetString(contents));             }               sb.AppendLine(boundary );             byte[] fulldata = Encoding.Default.GetBytes(sb.ToString());            // httpclient.ContentLength == fulldata.Length;             using (Stream sw = httpclient.GetRequestStream()) {     sw.Write(fulldata, 0, fulldata.Length); }             try {     HttpWebResponse response = httpclient.GetResponse() as HttpWebResponse;     using (StreamReader sr = new StreamReader(response.GetResponseStream())) {         //MessageBox.Show(sr.ReadToEnd());     } } catch (WebException ex) {     using (StreamReader sr = new StreamReader(ex.Response.GetResponseStream())) {         //MessageBox.Show("Error Message:" + e.Message + Constants.vbCr + Constants.vbLf + "Error Body: " + sr.ReadToEnd(), "Web Error", MessageBoxButtons.OK, MessageBoxIcon.Error);     } }       i got an error in that code:The remote server returned an error: (400) Bad Request. please provide the my csv file is correct or not an if i can change my code? ... View more

i am faceing the Same problem please give  fix it.  below is my code and csv file HttpWebRequest httpclient = (HttpWebRequest)WebRequest.Create("https://api.constantcontact.com/v2/activities/addcontacts?api_key=wv7crkj3rk3gy52ykqegkxqq"); string boundary = "--" + Guid.NewGuid().ToString(); string filename = "F:\\constant contact Wrapper\\Constant.csv"; httpclient.Headers.Add("Authorization", "Bearer 2269f201-044b-45f7-8015-e5e107555dd5"); // httpclient.Headers.Add("Accept", "application/json"); // httpclient.Headers.Add("content-type", "multipart/form-data"); // File fileToUse = new File(); // FileBody data = new FileBody(fileToUse); httpclient.Method = "POST"; httpclient.ContentType = string.Format("multipart/form-data"); httpclient.Accept = "application/json"; httpclient.PreAuthenticate = true; //string filename = "C:\\Development\\constantcontact\\emailkust.csv"; StringBuilder sb= new StringBuilder(); sb.AppendLine(boundary); sb.AppendLine("content-disposition: form-data; name="+filename +""); sb.AppendLine(); sb.AppendLine("Constant.csv"); //'filename sb.AppendLine(boundary); sb.AppendLine("content-disposition: form-data");//; name=""lists"""); sb.AppendLine(); sb.AppendLine("1") ;//' List Number sb.AppendLine(boundary); // sb.AppendLine("content-disposition: file; name=""data"" filename=""emailkust.csv"""); sb.AppendLine("Content-Type: text/csv"); sb.AppendLine(); using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read)) { byte[] contents = new byte[fs.Length]; fs.Read(contents, 0, contents.Length); sb.Append(Encoding.Default.GetString(contents)); } sb.AppendLine(boundary ); byte[] fulldata = Encoding.Default.GetBytes(sb.ToString()); // httpclient.ContentLength == fulldata.Length; using (Stream sw = httpclient.GetRequestStream()) { sw.Write(fulldata, 0, fulldata.Length); } try { HttpWebResponse response = httpclient.GetResponse() as HttpWebResponse; using (StreamReader sr = new StreamReader(response.GetResponseStream())) { //MessageBox.Show(sr.ReadToEnd()); } } catch (WebException ex) { using (StreamReader sr = new StreamReader(ex.Response.GetResponseStream())) { //MessageBox.Show("Error Message:" + e.Message + Constants.vbCr + Constants.vbLf + "Error Body: " + sr.ReadToEnd(), "Web Error", MessageBoxButtons.OK, MessageBoxIcon.Error); } } ... View more