从TLS 1.2仅端点请求时的HttpClient异常

Question

Does anyone know how to get HttpClient to work with a site that only supports TLS 1.2. I've verified with SSL Labs, https://www.ssllabs.com/ssltest/analyze.html?d=sandbox.paypal.com , that paypal has turned off all but TLS 1.2 on their sandbox site.

When I run the following code, I get an exception with the message, "The remote certificate is invalid according to the validation procedure."

var client = new HttpClient();
var content = client
    .GetAsync("https://sandbox.paypal.com/")
    .Result;

Answer 1

Their certificate is valid for www.sanbox.paypal.com but not for sandbox.paypal.com . Either add 'www' to the request URI or use custom certificate validation callback, like:

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