Fatal error: Uncaught Error: Non-static method tc_calendar::check_json_decode() cannot be called statically in /homepages/20/d361563030/htdocs/clickandbuilds/MusikfabrikSteinfurt/wp-content/plugins/appointment-calendar/calendar/calendar_form.php:32 Stack trace: #0 {main} thrown in /homepages/20/d361563030/htdocs/clickandbuilds/MusikfabrikSteinfurt/wp-content/plugins/appointment-calendar/calendar/calendar_form.php on line 32