The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel

问题

I am developing a Metro style app using C# and xaml.

In my application I got the error when calling to a web service:

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

What is the reason for this error?

回答1:

I have a crawler program and a few moments ago I got the same exception. The reason in my case is that the security certificate (of the site I have been crawling) expired.

A quick fix in my case was adding this line of code:

 ServicePointManager.ServerCertificateValidationCallback = new
RemoteCertificateValidationCallback
(
   delegate { return true; }
);

Note: this hack could be a security threat

来源：https://stackoverflow.com/questions/13071440/the-underlying-connection-was-closed-could-not-establish-trust-relationship-for