Fatal error: Uncaught Error: Call to undefined function add_shortcode() in /home/kacperg/public_html/kacpergr/wp-content/plugins/rsvp/external-libs/wp-simple-nonce/wp-simple-nonce.php:16 Stack trace: #0 /home/kacperg/public_html/kacpergr/wp-content/plugins/rsvp/wp-rsvp.php(115): require_once() #1 {main} thrown in /home/kacperg/public_html/kacpergr/wp-content/plugins/rsvp/external-libs/wp-simple-nonce/wp-simple-nonce.php on line 16