Fatal error: Uncaught Error: Class 'PHPExcel_Writer_Abstract' not found in C:\xampp\htdocs\enercard\vendor\phpoffice\phpexcel\Classes\PHPExcel\Writer\OpenDocument.php:28 Stack trace: #0 {main} thrown in C:\xampp\htdocs\enercard\vendor\phpoffice\phpexcel\Classes\PHPExcel\Writer\OpenDocument.php on line 28