Fatal error: Uncaught Error: Class "WP_Widget_Block" not found in /wp-includes/class-wp-widget-factory.php:61
Stack trace:
#0 /wp-includes/widgets.php(115): WP_Widget_Factory->register('WP_Widget_Block')
#1 /wp-includes/widgets.php(1847): register_widget('WP_Widget_Block')
#2 /wp-includes/class-wp-hook.php(307): wp_widgets_init('')
#3 /wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)
#4 /wp-includes/plugin.php(474): WP_Hook->do_action(Array)
#5 /wp-settings.php(587): do_action('init')
#6 /wp-config.php(101): require_once('/wp-settings.ph...')
#7 /wp-load.php(50): require_once('/wp-config.php')
#8 /wp-blog-header.php(13): require_once('/wp-load.php')
#9 /index.php(17): require('/wp-blog-header...')
#10 {main}
thrown in /wp-includes/class-wp-widget-factory.php on line 61