cURL SSL unable to get local issuer certificate on Xampp
Try to use the latest "Certificate data from Mozilla" bundle.
http://curl.haxx.se/ca/cacert.pem
Seems like it has most of the common CAs included.
Set in your php.ini
curl.cainfo=<path-to>cacert.pem
And restart XAMPP / Apache Module.
Double check with
phpinfo();
That your curl.cainfo is set correctly.