我有一个现有的WordPress网站，效果很好。突然，我无法登录管理员面板，发现了这个错误：
Fatal error: Class 'Mfn_Tag_Cloud_Widget' not found in /public_html/wp-includes/class-wp-widget-factory.php on line 106
我使用WP插件提取备份并在新的WP安装上恢复它，但我也遇到了同样的错误。
任何帮助！？
完整的错误消息：
Fatal error: Uncaught Error: Class 'Mfn_Tag_Cloud_Widget' not found in ..\wp-includes\class-wp-widget-factory.php:106 Stack trace: #0 ..\wp-includes\widgets.php(113): WP_Widget_Factory->register('Mfn_Tag_Cloud_W...') #1 ..\wp-content\themes\MyTheme\functions\widget-functions.php(21): register_widget('Mfn_Tag_Cloud_W...') #2 ..\wp-includes\class-wp-hook.php(298): mfn_register_widget('') #3 ..\wp-includes\class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array) #4 ..\wp-includes\plugin.php(453): WP_Hook->do_action(Array) #5 ..\wp-includes\widgets.php(1474): do_action('widgets_init') #6 ..\wp-includes\class-wp-hook.php(298): wp_widgets_init('') #7 ..\wp-includes\class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array) #8 ..\wp-includes\plugin.php(453): WP_Hook->do_action(Array) #9 ..\wp-includes\class-wp-widget-factory.php on line 106