I set "Secure Protocol" in the app as required:
ServicePointManager.ServerCertificateValidationCallback += ValidateCertificate;
ServicePointManager.SecurityProtocol =
SecurityProtocolType.Tls |
SecurityProtocolType.Tls11 |
SecurityProtocolType.Tls12 |
SecurityProtocolType.Ssl3;
try {
} finally {
ServicePointManager.ServerCertificateValidationCallback -= ValidateCertificate;
}
private static bool ValidateCertificate(
Object sender, X509Certificate cert, X509Chain chain,
SslPolicyErrors Errors ) {
return true;
}