Fixing URL error 60: SSL certificate problem: unable to get local issuer certificate

Download curl certificate file at
http://curl.haxx.se/ca/cacert.pem

Copy and paste the dowloaded file into c:/xampp/php or whatever your php folder is located.

You certificate file should be located at /opt/lamp/php/cacert.pem if you're using lampstack on linux.

And point your S3 SSL path to the following directory for linux.

S3_SSL_PATH=/opt/lampstack-5.5.31-0/php/cacert.pem

Add the following line into the bottom of the php.ini file
[cURL]
curl.cainfo="C:\xampp\php\cacert.pem"