ASP.NET和底层连接已关闭：无法为SSL / TLS安全通道建立信任关系

我正在使用公共Root权威证书文件X509制作httpwebrequest.我只有公钥,而不是私钥.从控制台应用程序一切正常,但它不适用于asp.net应用程序.我收到错误：“底层连接已关闭：无法为SSL / TLS安全通道建立信任关系.”

禁用验证的选项不是一个选项.

这是代码

HttpWebRequest req = (HttpWebRequest)WebRequest.Create("https://xxxxxxx/gateway.aspx");
string post = "abcdef";
req.ContentType = "application/x-www-form-urlencoded";
req.Method = "POST";
req.ContentLength = post.Length;

var cert = System.Security.Cryptography.X509Certificates.X509Certificate.CreateFromCertFile(@"c:temproot.cer");

req.ClientCertificates.Add(cert);
StreamWriter stOut = new StreamWriter(req.GetRequestStream(),System.Text.Encoding.ASCII);
stOut.Write(post.ToString());
stOut.Close();

HttpWebResponse resp = (HttpWebResponse)req.GetResponse();

这是System.Net和System.Net套接字的系统日志.

System.Net信息：0：[5928] SecureChannel#8106798 – 无法将证书链构建到受信任的根颁发机构.

System.Net信息：0：[5928] SecureChannel#8106798 – 远程证书被用户验证为无效.

System.Net.Sockets详细：0：[5928]套接字#7486778 :: Dispose()

System.Net错误：0：[5928] HttpWebRequest中的异常#51319244 :: – 底层连接已关闭：无法为SSL / TLS安全通道建立信任关系.

System.Net错误：0：[5928] HttpWebRequest中的异常#51319244 :: EndGetRequestStream – 底层连接已关闭：无法为SSL / TLS安全通道建立信任关系.

更多信息

如果我使用此代码(来自CodeGuru)

public static bool ValidateServerCertificate(object sender,X509Certificate certificate,X509Chain chain,SslPolicyErrors sslPolicyErrors)
  {
     if (sslPolicyErrors ==
        SslPolicyErrors.RemoteCertificateChainErrors) {
        return false;
     } else if (sslPolicyErrors ==
        SslPolicyErrors.RemoteCertificateNameMismatch) {
        System.Security.Policy.Zone z =
           System.Security.Policy.Zone.CreateFromUrl
           (((HttpWebRequest)sender).RequestUri.ToString());
        if (z.SecurityZone ==
           System.Security.SecurityZone.Intranet ||
           z.SecurityZone ==
           System.Security.SecurityZone.MyComputer) {
           return true;
        }
        return false;
     }
     return true;
  }

我最终得到错误：

Remote Certificate Chain Error

ServicePointManager.ServerCertificateValidationCallback += (sender,certificate,chain,sslPolicyErrors) => true;