Fatal error: Uncaught Error: Class 'WP_Widget' not found in /nfs/aesop1/hw00/d67/cerse/wordpress/wp-includes/widgets/class-wp-widget-calendar.php:17 Stack trace: #0 {main} thrown in /nfs/aesop1/hw00/d67/cerse/wordpress/wp-includes/widgets/class-wp-widget-calendar.php on line 17