Fatal error: Uncaught Facebook\Exceptions\FacebookSDKException: Required "app_id" key not supplied in config and could not find fallback environment variable "FACEBOOK_APP_ID" in /var/www/html/core/library/facebook/Facebook.php:139 Stack trace: #0 /var/www/html/core/controllers/facebook.php(36): Facebook\Facebook->__construct(Array) #1 /var/www/html/core/app.php(162): require('/var/www/html/c...') #2 /var/www/html/index.php(25): require('/var/www/html/c...') #3 {main} thrown in /var/www/html/core/library/facebook/Facebook.php on line 139