Fatal error: Uncaught Error: Class "PKP\handler\APIHandler" not found in C:\xampp\htdocs\ojs\lib\pkp\api\v1\mailables\MailableHandler.php:29 Stack trace: #0 {main} thrown in C:\xampp\htdocs\ojs\lib\pkp\api\v1\mailables\MailableHandler.php on line 29