Fatal error: Uncaught Error: Call to undefined function add_action() in /home/wmichal67/public_html/lekcjatest-1v-mw/wp-includes/blocks/calendar.php:93 Stack trace: #0 {main} thrown in /home/wmichal67/public_html/lekcjatest-1v-mw/wp-includes/blocks/calendar.php on line 93