Fatal error: Uncaught Error: Class 'WP_Widget_Block' not found in /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/class-wp-widget-factory.php:61 Stack trace: #0 /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/widgets.php(115): WP_Widget_Factory->register('WP_Widget_Block') #1 /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/widgets.php(1802): register_widget('WP_Widget_Block') #2 /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/class-wp-hook.php(303): wp_widgets_init('') #3 /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters(NULL, Array) #4 /export/sd205/www/jp/r/e in /export/sd205/www/jp/r/e/gmoserver/5/6/sd0260556/test.maruc-group.jp/wordpress-5.5.3-ja-jetpack_webfont-undernavicontrol/wp-includes/class-wp-widget-factory.php on line 61