无法从传输连接读取数据：现有连接被远程主机强制关闭

当我尝试从 morizo​​n.pl 下载源页面时遇到问题：

  WebClient webClient = new WebClient();
  try
  {
      string str = webClient.DownloadString("https://www.morizon.pl/");
  }
  catch (Exception ex)
  {
      Console.WriteLine(ex);
  }

我在 stackoverflow 中检查了类似的问题并编辑了我的代码，但仍然没有任何结果，我陷入了这个问题。

public class CookieAwareWebClient : WebClient
{
    public CookieContainer CookieContainer { get; set; }

    public CookieAwareWebClient()
        : this(new CookieContainer())
    { }

    public CookieAwareWebClient(CookieContainer c)
    {
        this.CookieContainer = c;
    }

    protected override WebRequest GetWebRequest(Uri address)
    {
        WebRequest request = base.GetWebRequest(address);
        var castRequest = request as HttpWebRequest;

        if (castRequest != null)
        {
            castRequest.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";
            castRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.104 Safari/537.36";
            castRequest.Headers.Add("Accept-Encoding", "gzip,deflate,sdch");
            castRequest.Headers.Add("Accept-Language", "en-GB,en-US;q=0.8,en;q=0.6");
            castRequest.KeepAlive = false;
            castRequest.ProtocolVersion = HttpVersion.Version10;
            castRequest.ServicePoint.ConnectionLimit = 1;
            castRequest.CookieContainer = this.CookieContainer;
        }

        return request;
    }
}

例如，我可以使用我的功能下载 google.com，但我不能下载 morizo​​n.pl。

从 .NET Framework 4.0 开始，默认安全协议是TLS 1.0 and SSL 3.0.

在您的应用程序中，您可能需要启用TLS 1.1 and/or TLS 1.2.

System.Net.ServicePointManager.SecurityProtocol |= 
    SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

using (WebClient webClient = new WebClient())
{
  string str = webClient.DownloadString("https://www.morizon.pl/");
}

更多细节在此堆栈溢出帖子 https://stackoverflow.com/questions/28286086/default-securityprotocol-in-net-4-5.