Fatal error: Uncaught Error: Class "PKP\pages\management\ManagementHandler" not found in C:\xampp\htdocs\ojs\lib\pkp\pages\management\PKPToolsHandler.php:31 Stack trace: #0 {main} thrown in C:\xampp\htdocs\ojs\lib\pkp\pages\management\PKPToolsHandler.php on line 31