What potential issues or errors might arise when trying to integrate the PHPExcel Class into the existing code?

One potential issue that might arise when trying to integrate the PHPExcel Class into existing code is namespace conflicts with other classes or libraries. To solve this, you can use namespaces to avoid conflicts and ensure that the PHPExcel Class is properly loaded and used in your code.

// Use namespaces to avoid conflicts
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

// Create a new Spreadsheet object
$spreadsheet = new Spreadsheet();

// Do something with the spreadsheet object

// Write the spreadsheet to a file
$writer = new Xlsx($spreadsheet);
$writer->save('output.xlsx');