Fatal error: Uncaught Error: Class "PhpOffice\PhpSpreadsheet\Writer\Xls\BIFFwriter" not found in D:\xampp\htdocs\phpOffice\PhpSpreadsheet\Writer\Xls\Worksheet.php:57 Stack trace: #0 {main} thrown in D:\xampp\htdocs\phpOffice\PhpSpreadsheet\Writer\Xls\Worksheet.php on line 57