Hello I'm using this method for API call (v1)

1. public static string AccessCRM(string url, string postcontent)
2.         {
3.                     //ServicePointManager.ServerCertificateValidationCallback = ValidateRemoteCertificate;
4.                     WebRequest request = WebRequest.Create(url);
5.                     request.Method = "POST";
6.                     byte[] byteArray = Encoding.UTF8.GetBytes(postcontent);
7.                     request.ContentType = "application/x-www-form-urlencoded";
8.                     request.ContentLength = byteArray.Length;
9.                     Stream dataStream = request.GetRequestStream();
10.                     dataStream.Write(byteArray, 0, byteArray.Length);
11.                     dataStream.Close();
12.                     WebResponse response = request.GetResponse();
13.                     dataStream = response.GetResponseStream();
14.                     StreamReader reader = new StreamReader(dataStream);
15.                     string responseFromServer = reader.ReadToEnd();
16.                     reader.Close();
17.                     dataStream.Close();
18.                     response.Close();
19.                     return responseFromServer;
20.           }
    

It was working before but now , it is returning an html instead of xml/json, I tried using POSTMAN or a browser to make a manual API call and it works

Need help ASAP, Thanks in advance