How to download older Mac OS X versions via the App Store
- Click the App Store icon.
- Click Purchases in the top menu.
- Scroll down to find the preferred OS X version.
- Click Download.
Can I download older versions of Mac OS?
Any old macOS you have won't run anymore, because the security certificates on them expired then. However, any old macOS installer that you can download from Apple now will work. ... For some years, Apple kept the old installers for versions such as El Capitan, Sierra and High Sierra in the App Store, but hid them.
Can you downgrade macOS?
Downgrade Using macOS Recovery
Assuming your Mac didn't come with the most recent version of macOS installed, downgrading is fairly easy. You can use the built-in macOS Recovery to downgrade. Just make sure you have internet access during the installation, as the software will download a previous version of macOS.