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 /sonesoft/www/Facebook/Facebook.php:139 Stack trace: #0 /sonesoft/www/lib/api.lib.php(90): Facebook\Facebook->__construct(Array) #1 /sonesoft/www/facebook_login.php(4): facebook_login_btn() #2 {main} thrown in /sonesoft/www/Facebook/Facebook.php on line 139