PhpSpreadsheet/docs/topics/migration-from-PHPExcel.md

Migration from PHPExcel

PhpSpreadsheet introduced many breaking changes by introducing namespaces and renaming some classes. To help you migrate existing project, a tool was written to replace all references to PHPExcel classes to their new names. But there are also manual changes that need to be done.

Automated tool

RectorPHP can be used to migrate automatically your codebase. Assuming your files to be migrated lives in src/, you can run the migration like so:

composer require rector/rector --dev
vendor/bin/rector process src --set phpexcel-to-phpspreadsheet
composer remove rector/rector

For more details, see RectorPHP blog post.