https://www.php-web-design.com/Joomla-Components/fool-proof-migrations-from-joomla-3-to-joomla-4-x.html
Fool-proof Migrations from Joomla 3 to Joomla 4.x
This Joomla! extension simplifies your migration process - ensuring no downtime, crashes, or "white screen of death."
With just one click, MigrateMe 4 will check your current Joomla 3.x system, apply updates, repair database issues, and create a standalone environment to safely test the new Joomla 4.
Enjoy all the latest features and seamless integration with third-party extensions, custom templates, and plugins.
Migrate your old data, files, and access with ease and start using Joomla 4 today!