Problem
CurlException: 60: SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
Solution
Adding the following code:
Facebook::$CURL_OPTS[CURLOPT_SSL_VERIFYPEER] = false;
Facebook::$CURL_OPTS[CURLOPT_SSL_VERIFYHOST] = 2;