Troubleshooting: 根據驗證程序，遠端憑證是無效的。

我想一定有人遇過這個問題，就是當使用 WebClient 或 WebRequest 類別抓取 HTTPS/SSL 的網頁時，出現以下錯誤訊息：

那是因為 .Net 針對安全的網路連線必須要有正確可受信任的憑證才可以連接！

如果你原本的程式長這樣：

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        WebClient client = new WebClient();

Stream data = client.OpenRead("https://www.securedomain.com.tw/index.aspx");
StreamReader reader = new StreamReader(data);

string s = reader.ReadToEnd();

data.Close();
reader.Close();

Response.Write(s);
}
}
[/code]

你只要改成這樣就可以忽略憑證檢查的步驟了！

[code:c#]
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Net;
using System.IO;

using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

public partial class _Default : System.Web.UI.Page
{
    // 設定 HTTPS 連線時，不要理會憑證的有效性問題
    public static bool ValidateServerCertificate(Object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
    {
        return true;
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        // 設定 HTTPS 連線時，不要理會憑證的有效性問題
        ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(ValidateServerCertificate);

WebClient client = new WebClient();

Stream data = client.OpenRead("https://www.securedomain.com.tw/index.aspx");
StreamReader reader = new StreamReader(data);

string s = reader.ReadToEnd();

data.Close();
reader.Close();

Response.Write(s);
}
}
[/code]

注意事項：