I have run into this issue when I was trying to configure a Laravel 5.2 application to send emails using Mailgun. I got an exception like this, when I was trying to send an email:

cURL error 60: SSL certificate problem: unable to get local issuer certificate

To solve this issue, you have to get a local certificate, and specify it’s location in the php.ini file.

Download the certificate

You can download the certificate from this url: http://curl.haxx.se/ca/cacert.pem. I saved it to the root directory of my PHP installation, but it can be anywhere.

Specify the certificate’s location in php.ini

In your php.ini file, specify the location of this certificate by setting (of course, using your actual path to the certificate):

curl.cainfo = C:\Software\php-7.0.2-x86\cacert.pem

Restart Apache and you are done.