May 2022 API Portal is bundled with a major new release of the Joomla platform, Joomla 4. This video explains an optional prerequisite which is only required if you are using a custom API Portal database adapter (mysqli_enc or mysqli_ssl).
Optional Prerequisites:
1. Switch to the standard MySQLi default database adapter before you upgrade to May 2022 and how to switch back post upgrade
Once all prerequisites are complete, you can run apiportal_upgrade.sh to upgrade API Portal to the May 2022 release.