Wordress Get All Categories using xmlrpc is not working

I am trying to get WordPress categories using the XML-RPC method and it’s working fine on my local as well as sandbox environment but not on production. I am using c# for the same and here is the code.

public JsonArray GetCateg(string username, string password){
 IgetCatList categories = (IgetCatList)XmlRpcProxyGen.Create(typeof(IgetCatList));
 XmlRpcClientProtocol clientProtocol = (XmlRpcClientProtocol)categories;
 //clientProtocol.Url = "https://samplewebsite12399.wordpress.com" + "/xmlrpc.php";
 clientProtocol.Url = url + "/xmlrpc.php";
 if (hasServiceUnavailable)
    clientProtocol.UserAgent = "WordPress XML-RPC Client/1.1";
    clientProtocol.KeepAlive = true;
    clientProtocol.Timeout = 42000;
  try
  {

     Category[] wpCategories = categories.GetCategories(1, username, password);
      return wpCategories;
  }
  catch(Exception ex){

  }
}

public interface IgetCatList
{
  [XmlRpcMethod("metaWeblog.getCategories")]
  Category[] GetCategories(int blog_id, string username, string password);
}

I am getting this error

{“message”:”Conflict”,”stacktrace”:” at xmlrpc.XmlRpcClientProtocol.ReadResponse(XmlRpcRequest req, WebResponse webResp, Stream respStm)\r\n at xmlrpc.XmlRpcClientProtocol.Invoke(Object clientObj, MethodInfo mi, Object[] parameters)\r\n at xmlrpc.XmlRpcClientProtocol.Invoke(MethodInfo mi, Object[] Parameters)\r\n at XmlRpcProxy9144647b-28c2-4d11-9ab9-35cd3f53ba20.GetCategories(Int32 blog_id, String username, String password)}?

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