HttpClient.SendAsync() 异常

如何解决HttpClient.SendAsync() 异常

在向不存在的端点发送请求时，我似乎无法捕获 HttpRequestException 或任何与此相关的异常。

http://localhost:8030/ 不存在，但是我应该能够在 try/catch 块中捕获 HttpRequestException。我错过了什么？

            Uri address = new Uri("http://localhost:8030/");
            HttpClient client = new HttpClient();
            var rm = new HttpRequestMessage()
            {
                Method = HttpMethod.Post,RequestUri = address
            };

            try
            {
                var response = await client.SendAsync(rm);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                throw;
            }

VSscreenshot