Fatal error: Uncaught Error: Call to undefined function add_filter() in /home/adaptyo3/public_html/wp-content/plugins/QUARENTINE/woocommerce-subscriptions/classes/class-wc-subscriptions-switcher.php:21 Stack trace: #0 /home/adaptyo3/public_html/wp-content/plugins/QUARENTINE/woocommerce-subscriptions/classes/class-wc-subscriptions-switcher.php(918): WC_Subscriptions_Switcher::init() #1 {main} thrown in /home/adaptyo3/public_html/wp-content/plugins/QUARENTINE/woocommerce-subscriptions/classes/class-wc-subscriptions-switcher.php on line 21