Fatal error: Uncaught Error: Class 'PhpOffice\PhpSpreadsheet\Worksheet\CellIterator' not found in /opt/lampp/htdocs/kuesioner/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Worksheet/ColumnCellIterator.php:8 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/kuesioner/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Worksheet/ColumnCellIterator.php on line 8