GitHub AE is constantly improving, with new functionality and bug fixes introduced through feature and patch releases. GitHub AE is a fully managed service, so GitHub completes the upgrade process for your enterprise.
Feature releases include new functionality and feature upgrades and typically occur quarterly. GitHub will upgrade your enterprise to the latest feature release. You will be given advance notice of any planned downtime for your enterprise.
Warning: The upgrade to a new feature release will cause a few hours of downtime, during which none of your users will be able to use the enterprise. You can inform your users about downtime by publishing a global announcement banner, using your enterprise settings or the REST API. For more information, see "Customizing user messages on your instance" and "GitHub Enterprise administration."