SSL certificate problem: self signed certificate in certificate chain

Go to http://curl.haxx.se/ca/cacert.pem and download the pem file and save in your php installation directory ( make sure while saving it retains the extension and not saved as a text file )

Now, open your php.ini file, scroll to the bottom and add the following line:

[cURL] 
curl.cainfo="D:\xampp\php\cacert.pem"

Replace D:\xampp\php\cacert.pem with the actual path.

https://laracasts.com/discuss/channels/laravel/how-to-solve-curl-error-60-ssl-certificate-in-laravel-5-while-facebook-authentication

http://stackoverflow.com/questions/17478283/paypal-access-ssl-certificate-unable-to-get-local-issuer-certificate