Warning: Use of undefined constant ABSPATH - assumed 'ABSPATH' (this will throw an Error in a future version of PHP) in E:\www\web\wp-admin\includes\class-wp-upgrader.php on line 13

Warning: require_once(ABSPATHwp-admin/includes/class-wp-upgrader-skin.php): failed to open stream: No such file or directory in E:\www\web\wp-admin\includes\class-wp-upgrader.php on line 13

Fatal error: require_once(): Failed opening required 'ABSPATHwp-admin/includes/class-wp-upgrader-skin.php' (include_path='E:\XAMPP\php\PEAR') in E:\www\web\wp-admin\includes\class-wp-upgrader.php on line 13