It works for me...
if (-not ([System.Management.Automation.PSTypeName]'ServerCertificateValidationCallback').Type)
{
$certCallback = @"
using System;
using System.Net;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
public class ServerCertificateValidationCallback
{
public static void Ignore()
{
if(ServicePointManager.ServerCertificateValidationCallback ==null)
{
ServicePointManager.ServerCertificateValidationCallback +=
delegate
(
Object obj,
X509Certificate certificate,
X509Chain chain,
SslPolicyErrors errors
)
{
return true;
};
}
}
}
"@
Add-Type $certCallback
}
[ServerCertificateValidationCallback]::Ignore()
Invoke-WebRequest -Uri https://apod.nasa.gov/apod/