How to downgrade from macOS 27 to macOS Tahoe
Short answer
Yes, but only by erasing the Mac and installing Tahoe fresh. Recovery's Reinstall option puts back the newest macOS, not the old one. Back up first, make a bootable Tahoe installer on a USB drive, erase and install from it, then copy your files back. If you made a Time Machine backup while still on Tahoe, you can restore everything from that.
On this page
Careful: downgrading erases the Mac. Make a full backup first, and check that you can open it.
Before you start
- Back up with Time Machine or a cloning app. A backup made on macOS 27 may not restore cleanly onto Tahoe, so also copy important files to a separate drive or to iCloud.
- Make sure you know your Apple Account password. You'll need it to turn off Activation Lock and sign in again.
- You need a USB drive of 32 GB or more, which will be erased.
1. Download the Tahoe installer
See which full installers are available, then download Tahoe by its version number:
softwareupdate --list-full-installers
softwareupdate --fetch-full-installer --full-installer-version 26.7.2The installer app appears in your Applications folder. Don't open it.
2. Make a bootable USB installer
Connect the USB drive and name it MyVolume in Disk Utility. Then run this (it erases the drive):
sudo "/Applications/Install macOS Tahoe.app/Contents/Resources/createinstallmedia" --volume /Volumes/MyVolume3. Erase and install Tahoe
- Shut down the Mac with the USB drive connected.
- Press and hold the power button until you see the startup options.
- Select the Tahoe installer and click Continue.
- Open Disk Utility, select Macintosh HD and click Erase.
- Quit Disk Utility, choose Install macOS Tahoe, and follow the steps.
4. Bring your files back
During setup, or later with Migration Assistant, restore from a Time Machine backup made while you were on Tahoe. If your only backup is from macOS 27, set up the Mac fresh and copy your files over by hand.
Another way: Apple Configurator
If you have a second Mac, you can restore a Tahoe image onto your Mac with Apple Configurator over a USB-C cable. This erases the Mac completely. Apple's guide covers the steps.
Other apps that can help
You don’t need any of these for the steps above. They go further in different ways, so pick what fits how you work.
| App | What it does | Price |
|---|---|---|
| Apple Configurator | Restore a Mac with a specific macOS version from a second Mac (DFU restore) | Free |
| Carbon Copy Cloner | Full backups of your data before erasing | Paid |
| Mist | Download full macOS installers and firmware for any version | Free, open source |
Sources and further reading
- Create a bootable installer for macOS · Apple Support
- Revive or restore a Mac with Apple silicon using Apple Configurator · Apple Support
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