How to find the exception error in uwp

string json = JsonConvert.SerializeObject(new
         {
             UN = UN,
             Pwd = Pwd,
             DTP = 1,
             OST = 1
         });
         WebClient wc = new WebClient();
         wc.Headers["Content-Type"] = "application/json";
         try
         {
             string response = wc.UploadString(endpoint, method, json);
             return JsonConvert.DeserializeObject<User>(response);
            // i got the username and password in response  the code is running correct
         }

         catch (Exception ex)
         //Exception error {"Cannot deserialize the current JSON array (e.g. [1,2,3]) into type 'Windows.System.User' because the type requires a JSON object (e.g. {\"name\":\"value\"}) to deserialize correctly.\r\nTo fix this error either change the JSON to a JSON object (e.g. {\"name\":\"value\"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List<T> that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.\r\nPath '', line 1, position 1."}
         {
             return null;
         }