My API uses RestSharp to call a REST API, and the code looks like this.

var testRequest = { My JSON Data}
var clientResponse = new RestClient(".....");
var callrequest = new RestRequest("....", Method.Post);
string authHeader = "...";

callrequest.AddParameter("application/json", testRequest, ParameterType.RequestBody);
callrequest.AddParameter("Authorization", "Bearer " + authHeader, ParameterType.HttpHeader);
var response = clientResponse.Execute(callrequest); <---- //Red line showing here
return Ok(response);

Error

I’m unable to run my software because of the red line. Could someone perhaps explain what the problem is?

Thank you very much.