ZohoDesk Ticket Creation on API not working ,

We have our website integrated with zohodesk API, this was working up until today.

I have spent most of day trying to figure this out so any help will be appreciated.

the service is written in

c# ,

and just trying to create a ticket with below code :

string postData1 = JsonConvert.SerializeObject(ticketSend);

Uri uri1;

HttpClient client1;

HttpResponseMessage message;

uri1 = new Uri("https://desk.zoho.com/api/v1/tickets");

client1 = new HttpClient();

client1.DefaultRequestHeaders.Add("orgId", ConfigurationManager.AppSettings["orgId"]);

client1.DefaultRequestHeaders.Add("Authorization", ConfigurationManager.AppSettings["Authorization"]);

message = client1.PostAsync(uri1, new StringContent(postData1, Encoding.UTF8, "application/json")).Result;

keep getting error

Unsupported Media Type

Please see my JSON object attached.

thxs