转载，原文来自 http://blog.csdn.net/hawksoft/article/details/21776009
最近调试原来的微信模拟登陆时发生了“基础连接已关闭，发送时发生错误”的错误提示，原来都是好好的，只是很久没用了。
出错代码如下：
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("https://mp.weixin.qq.com/cgi-bin/loginpage?t=wxm2-login&lang=zh_CN");///cgi-bin/loginpage?t=wxm2-login&lang=zh_CN
req.CookieContainer = cookie;
req.Method = "GET";
req.ProtocolVersion = HttpVersion.Version10;
HttpWebResponse res = (HttpWebResponse)req.GetResponse();
StreamReader rd = new StreamReader(res.GetResponseStream());
string theContent = rd.ReadToEnd();
经过一番Google和试验，答案既如此简单，增加如下一句：
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
通过代码如下：
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("https://mp.weixin.qq.com/cgi-bin/loginpage?t=wxm2-login&lang=zh_CN");///cgi-bin/loginpage?t=wxm2-login&lang=zh_CN
req.CookieContainer = cookie; req.Method = "GET"; req.ProtocolVersion = HttpVersion.Version10; ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3; HttpWebResponse res = (HttpWebResponse)req.GetResponse(); StreamReader rd = new StreamReader(res.GetResponseStream()); string theContent = rd.ReadToEnd();
[转载]使用HttpWebRequest进行请求时发生错误：基础连接已关闭，发送时发生错误处理
原文：http://www.cnblogs.com/hhh/p/4772731.html