Fatal Error

I am using the WordPress Multi-Language plugin and am getting the error show below when I try sync the menus on my website.They are not translating for some reason.

Fatal error: Call to a member function _save() on a non-object in /home4/mvaorg/public_html/wp-content/themes/pb-theme/lib/carbon-fields/core/Container/Nav_Menu_Container.php on line 164

Is this code essential for the Nav_Menu_Container.php file?

/**
* Trigger Save for all instances
*/
public static function update( $menu_id, $current_menu_item_id ) {
$instance = self::set_instance_for_id( $current_menu_item_id, false );
$instance->_save();

return $instance;
}

Thanks in advance

https://ww.wp.xz.cn/plugins/carbon-fields/