No MediaTypeFormatter 'text / html' available

I wrote a ServiceHelper class that will help POST in a C # web API controller.

public class ServiceHelper<TResponse, TRequest> : IServiceHelper<TResponse, TRequest>
{
    public TResponse Execute
        (
        string endpoint, 
        string controller, 
        string action, 
        TRequest request,
        string format = "application/json"
        )
    {
        using (var httpClient = new HttpClient())
        {
            httpClient.BaseAddress = new Uri(endpoint);
            httpClient.DefaultRequestHeaders.Accept.Clear();
            httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(format));

            var response = httpClient.PostAsJsonAsync(String.Format("{0}/{1}", controller, action),
                request).Result;

            return response.Content.ReadAsAsync<TResponse>().Result;
        }
    }
}

      

        
        
        
      

    

I keep getting

Additional information: No MediaTypeFormatter is available to read an object of type 'ReadMotorVehiclesWorkflowResponse' from content with media type 'text/html'.

      

        
        
        
      

    

Any ideas on how to fix this?