Warning: session_start(): Failed to read session data: user (path: \xampp\tmp) in C:\xampp\htdocs\myarea\libraries\joomla\session\session.php on line 665

Fatal error: Cannot use Joomla\String\String as String because 'String' is a special class name in C:\xampp\htdocs\myarea\libraries\vendor\joomla\registry\src\Format\Json.php on line 12