Fatal error: Uncaught Error: Undefined constant "PKP\metadata\PKP_STRICT_MODE" in C:\xampp\htdocs\ojs\lib\pkp\classes\metadata\MetadataProperty.php:542 Stack trace: #0 {main} thrown in C:\xampp\htdocs\ojs\lib\pkp\classes\metadata\MetadataProperty.php on line 542