Fatal error: Uncaught Error: Call to undefined function add_filter() in /var/www/andovercg/staging/wp-content/themes/astra/inc/addons/scroll-to-top/classes/class-astra-scroll-to-top-loader.php:41 Stack trace: #0 /var/www/andovercg/staging/wp-content/themes/astra/inc/addons/scroll-to-top/classes/class-astra-scroll-to-top-loader.php(29): Astra_Scroll_To_Top_Loader->__construct() #1 /var/www/andovercg/staging/wp-content/themes/astra/inc/addons/scroll-to-top/classes/class-astra-scroll-to-top-loader.php(134): Astra_Scroll_To_Top_Loader::get_instance() #2 {main} thrown in /var/www/andovercg/staging/wp-content/themes/astra/inc/addons/scroll-to-top/classes/class-astra-scroll-to-top-loader.php on line 41