How to downgrade macOS

Before you downgrade macOS

• Back up. Make a fresh Time Machine backup now: see how to back up a Mac. If you also have a backup made before the upgrade, keep it.
• Check which Mac you have. Choose Apple menu › About This Mac. Chip means Apple silicon, Processor means Intel.
• Check how far back you can go. A Mac can’t run a macOS older than the one it came with. This applies to Macs with Apple silicon too.

Download the earlier macOS installer

Do this while your Mac still works. To see which full installers Apple offers for your Mac, open Terminal and run:

Pick a version from the list and download it with softwareupdate --fetch-full-installer --full-installer-version followed by its number. The installer, named Install macOS with the version’s name, appears in the Applications folder. Apple’s page “How to download macOS” also has App Store links for older versions.

Make a bootable USB installer

1. Connect a USB drive of 32 GB or more and rename it MyVolume in Finder.
2. Open Terminal and paste the command below. It is for macOS Sequoia: for another version, put its name in place of Sequoia.
3. Press Return, enter your Mac password, type Y to confirm and wait until Terminal says it’s done.

This command erases everything on the USB drive and copies the installer to it. Nothing on your Mac’s own disk changes:

Erase the Mac and install the earlier macOS

These steps delete everything on the Mac. Check your backup before you start:

1. Start up in macOS Recovery: see how to start a Mac in Recovery Mode.
2. Select Disk Utility and click Continue. Select Macintosh HD, click Erase, then Erase Volume Group (or Erase). Follow the onscreen steps, then shut down the Mac.
3. Connect the USB installer. On a Mac with Apple silicon, press and hold the power button until the startup options appear, select the installer and click Continue. On an Intel Mac, turn it on and immediately hold Option, select the installer and press Return.
4. Choose to install macOS, click Continue and select Macintosh HD as the disk.
5. When Setup Assistant offers to transfer information, choose your Time Machine backup.

On an Intel Mac with the Apple T2 Security Chip, the Mac starts from a USB drive only if Startup Security Utility allows booting from external media. On an Intel Mac you can also skip the USB drive: start Recovery with Shift-Option-Command-R and choose Reinstall macOS to get the macOS your Mac came with, or the closest version still available.

Which backup to restore

• A backup made before the upgrade brings back your apps, files and settings as they were then.
• Files you created or changed after that backup aren’t in it. Copy them to a separate drive before you erase the Mac and put them back afterwards.