Fatal error: Uncaught Error: Call to undefined function add_action() in /home/k1818436/public_html/wp-content/plugins/pdf-viewer-for-wordpress/includes/tinymce/button.php:14 Stack trace: #0 {main} thrown in /home/k1818436/public_html/wp-content/plugins/pdf-viewer-for-wordpress/includes/tinymce/button.php on line 14