private void SetRequestHeaders(string tcHost, string tcUserName, string tcPassword, int tnTimeout, int tnRetries) { client.DefaultRequestHeaders.Accept.Clear(); client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); client.BaseAddress = new Uri(tcHost); client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue( "Basic", Convert.ToBase64String( System.Text.ASCIIEncoding.ASCII.GetBytes( string.Format("{0}:{1}", tcUserName, tcPassword)))); client.DefaultRequestHeaders.CacheControl = new CacheControlHeaderValue() { MaxAge = TimeSpan.Zero }; client.Timeout = TimeSpan.FromSeconds( tnTimeout); }just added a line about CacheControl.