await運算符只能用於異步方法中。請考慮用async修飾符標記此方法，並將其返回類型更改為Task...

        private void button1_Click(object sender, EventArgs e) { string url = "http://localhost:35234/api/Products"; //創建HttpClient（注意傳入HttpClientHandler） var handler = new HttpClientHandler() { AutomaticDecompression =System.Net.DecompressionMethods.GZip }; using (HttpClient http = new HttpClient(handler)) { //await異步等待回應 HttpResponseMessage response = await http.GetAsync(url); //確保HTTP成功狀態值  response.EnsureSuccessStatusCode(); //await異步讀取最后的JSON（注意此時gzip已經被自動解壓縮了，因為上面的AutomaticDecompression = DecompressionMethods.GZip） Console.WriteLine(await response.Content.ReadAsStringAsync()); } }

出現錯誤，按提示進行修改

 

        private async void button1_Click(object sender, EventArgs e)