HttpWebRequest始终返回415（UnsupportedMediaType）

Question

有问题： 当使用HttpWebRequest服务器发送PUT请求时，始终返回415错误， 在Fiddler标头“ Content-Type”中，出现值“ application / json”，而不是全部 一定可以。但是在此代码的.NET变体中，所有操作都很好，这是我的错误，代码示例如下。在POSTMAN中一切正常 提前谢谢。

url := 'url';
body := '{"status": "NEW_STATUS"}';

NetCcredentials := NetCcredentials.NetworkCredential('login', 'password');

HttpWebRequest := HttpWebRequest.Create(url);
HttpWebRequest.Method := 'PUT';
HttpWebRequest.ContentType := 'application/json; charset=utf8';
HttpWebRequest.Timeout := 6000;
HttpWebRequest.Credentials := NetCcredentials;
HttpWebRequest.KeepAlive := TRUE;

RequestStr := HttpWebRequest.GetRequestStream;

StreamWriter := StreamWriter.StreamWriter(RequestStr,Encoding.UTF8);
StreamWriter.Write(body);
StreamWriter.Flush;
StreamWriter.Close;
StreamWriter.Dispose;

HttpWebResponse:=HttpWebRequest.GetResponse;
MESSAGE(HttpWebResponse.StatusCode.ToString);