Fatal error: Uncaught Error: Class 'PhpOffice\PhpSpreadsheet\Writer\Xls\BIFFwriter' not found in /var/www/html/portal/phpspreadsheet_exc/src/PhpSpreadsheet/Writer/Xls/Worksheet.php:55 Stack trace: #0 {main} thrown in /var/www/html/portal/phpspreadsheet_exc/src/PhpSpreadsheet/Writer/Xls/Worksheet.php on line 55