The request was aborted: Could not create SSL/TLS secure channel

I finally found the answer (I haven't noted my source but it was from a search);

While the code works in Windows XP, in Windows 7, you must add this at the beginning:

// using System.Net;ServicePointManager.Expect100Continue = true;ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;// Use SecurityProtocolType.Ssl3 if needed for compatibility reasons

And now, it works perfectly.

ADDENDUM

As mentioned by Robin French; if you are getting this problem while configuring PayPal, please note that they won't support SSL3 starting by December, 3rd 2018. You'll need to use TLS. Here's Paypal page about it.

The solution to this, in .NET 4.5 is

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

If you don’t have .NET 4.5 then use

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

Make sure the ServicePointManager settings are made before the HttpWebRequest is created, else it will not work.

Works:

ServicePointManager.Expect100Continue = true;ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls       | SecurityProtocolType.Tls11       | SecurityProtocolType.Tls12       | SecurityProtocolType.Ssl3;HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://google.com/api/")

Fails:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://google.com/api/")ServicePointManager.Expect100Continue = true;ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls       | SecurityProtocolType.Tls11       | SecurityProtocolType.Tls12       | SecurityProtocolType.Ssl3;