High Sierra has been out since September 2017, and the next version - macOS Mojave - is already in beta, with a public launch expected this autumn. We think High Sierra was a great update to the Mac operating system, with some great features such as some iOS inspired changes in the Photos app, and improvements to the Mail and Notes apps. It took a while for some of the new capabilities to arrive - such as Messages in iCloud, which arrived in June 2018, but all in all, this was a worthwhile update (especially since it’s free).
However, there may well be reasons why you need to revert to an older version of the Mac operating system. Perhaps you only recently bit the bullet and upgraded only to discover that an app you rely on doesn’t work.
Or maybe you need to run an older version of the macOS on a Mac you are using to testing apps as part of your job. In which case you may be looking to downgrade a Mac, or to run multiple operating systems on the same machine.
Unfortunately downgrading to an older version of macOS (or Mac OS X as it was previously known) isn’t as simple as finding the older version of the Mac operating system and reinstalling it. Once your Mac is running a newer version it won’t allow you to downgrade it that way. But it is still possible to downgrade your Mac.
We’ll run through the steps to downgrade your Mac in this article. If you are wanting to downgrade from a beta version of macOS we have a separate article dealing with downgrading from a beta version of macOS here.
What you need to do before you downgrade macOS
Before you start the process of downgrading your Mac, you must back up.
During the downgrade process you will completely wipe your hard drive so if there is anything you don’t want to lose make sure you have a copy of it.
If you have been using Time Machine (with your backup drive plugged in) it should have been making regular backups of your Mac, which should stand you in good stead. At the very least, if you made a backup of your Mac prior to upgrading to High Sierra (which we always advise), you will have a version you can recover your Mac from, in which case you only need to make a copy of any new files added since.
If you don’t have a backup, don’t assume that you can back up now that you are running High Sierra, because if you recover your Mac from a High Sierra back up it will recover High Sierra too and you will be back at square one. For that reason any new files you have created since installing High Sierra will need to be backed up separately.
Before you turn your back on High Sierra, you might want to consider running two versions of MacOS on your Mac. You could create a partition and run an older version of the Mac operating system on one, and High Sierra on the other. Read about how to install multiple versions of MacOS on your Mac here.
How to downgrade to the OS that shipped on your Mac
This has been a feature in macOS Recovery since macOS Sierra 10.12.4 and it might work for you (although it didn’t work for us).
Apple explains that you should shut down your Mac and then as you restart press shift-Option/Alt-Command-R all together (this is not easy one handed!).
This command will reinstall whatever version of the macOS your Mac shipped with, according to Apple.
Here are the steps Apple describes:
- Start up your Mac pressing shift-Option/Alt-Command-R.
- Once you see the macOS Utilities screen choose the Reinstall macOS option.
- Click Continue and follow the on screen instructions.
- Select your startup disk and click Install.
- Your Mac will restart once the installation is complete.
How to downgrade MacOS using a Time Machine backup
If the method above doesn't work for you, the simplest way to reverse an OS update is to restore from an earlier Time Machine backup - one you made before upgrading to High Sierra. If you prefer to use an alternative to Time Machine, such as the free Carbon Copy Cloner, you should still be able to revert to the older version of the OS using our guide.
It needs to be a complete backup of your system from before the upgrade. That backup can be on a directly connected external disk, hooked up by USB, FireWire or Thunderbolt. Or it can be on a Time Machine compatible network drive, like Apple's Time Capsule.
Before we begin, it's important to note that when you restore from a backup, you'll wipe everything on your startup disk. That means any work you've done since you upgraded to High Sierra will be lost (that might include songs you'd imported to iTunes, or photos you'd added to Photos).
So… back it up to a spare external drive or at the very least make a copy of any files you've created or modified since you upgraded. If you've got photos in the Photos app and you don't use iCloud Library, manually export them to an external disk so you can re-import them later.
- Plug your Time Machine disk into your Mac, click on the Apple logo > Restart.
- Hold down Command + R until the Apple logo appears.
- When the options appear on screen, choose 'Restore From Time Machine Backup' and click Continue.
- The next screen will show the words Restore from Time Machine, click Continue again.
- Next select your Restore Source - your backup drive.
- The next screen shows all your backups over time, pick the last one you made prior to updating to the newer version of the Mac operating system. (You can see which version of macOS the back up was made in).
Now that you have restored the older version of macOS or Mac OS X you can recover the files you created since from your separate backup.
How to downgrade MacOS without a Time Machine backup
If you didn’t make a back up prior to upgrading, it is still possible to downgrade, but it’s a little more complicated.
One option is to downgrade using a bootable installer. We explain how to create a bootable installer of macOS here.
If you don’t have the version of Mac OS you need here’s how to get an old version of Mac OS X.
Once you have a bootable installer of the version of MacOS (or Mac OS X ) you want to revert to, you are all set to install the older version of the Mac operating system. Note that this will involve erasing your startup drive, so make a backup of anything you don’t want to lose first. You cannot install a newer version of macOS on top of any later operating system so your startup volume has to be erased first.
- Shut down your Mac.
- Plug in the external drive that contains your bootable installer.
- Start up the Mac holding down the Option/Alt+R while it is booting up.
- When your Mac starts up it will be in Recovery mode and you’ll see a macOS Utilities screen showing the following options: Restore from Time Machine Backup, Reinstall macOS, Get Help Online and Disk Utility.
- Select Disk Utility.
- Click Continue.
- Select your Startup Disk.
- Click on Erase. You need to choose one of the Mac OS Extended (Journaled) formats.
- Now that the startup volume has been erased, restart your Mac holding down Alt/Option and select the boot drive you created.
Now you should be able to install the older version of the operating system following these steps.
How to downgrade from APFS to HFS+
As we said above, it may be a little more complicated if you are reverting from Mojave or High Sierra to a version of the macOS that predates them because Apple switched to a new file system (at least on SSD-equipped Macs). You can expect Fusion Drives and Hard Drives to have a similar file system change in macOS Mojave.
When Apple stopped trying to make APFS work on Fusion Drives back when it was beta testing High Sierra (an early version of the beta did support it on Fusion Drives), the company issued the following instructions to downgrade from the APFS version to a HFS+ version.
It is possible that you may have to follow these instructions in downgrading if you are using a Fusion Drive or a hard drive as Apple has confirmed that it will be attempting to get APFS working on these formats.
- Create a bootable installer as above.
- Press Option/Alt as you start up your Mac.
- Choose the bootable installer as your startup disk.
- Select Disk Utility.
- Choose Show All Devices.
- Choose your drive and click on Erase.
- Change the format to MacOS Extended (Journaled).
- Change the name of your drive to something else.
- Quit Disk Utility.
- Choose Reinstall macOS and select the new drive name as your target.
- Once in Setup Assistant choose to migrate your data from your Time Machine back up (Time Machine isn’t using APFS, yet, so this should work, for now).
Fixing problems when you downgrade macOS
Reversing an upgrade carries with it a number of wrinkles and pitfalls.
Most of these are due to changes in file formats and settings between versions of the OS. So, for example, if you create a document or work on a file in a new version, whether it's a beta or full release, of macOS and then try and open it in an older version, it may not work.
To mitigate this, it's wise to export any documents you've created or worked on in the newer OS in a standard file format. So, for example, if you use Scrivener or Ulysses, export documents as RTF files. That way, if the native files don't survive the reverse upgrade, you'll be able to re-import the RTF files.
Take screenshots of preferences and settings
Whenever you perform a clean install of macOS, which is what you're doing here, it's a good idea to take screenshots of any custom settings you've created in apps or in System Preferences. That makes it easier to re-create them later.
You should also make a note of user account and password details for anything you've set up while running the new version of the OS. If you don't use iCloud or Chrome to synchronise bookmarks, it's a good idea to export those and make a copy.
And unless you're using the migrate data option outlined above, you'll also need installers and licence codes for apps you use. If those are downloads from the Mac App Store, you can just re-download them from the Purchased section in the App Store. If not, make sure you can download them from the vendor's website. If you don't use a password manager to store licence codes, make sure you've got a copy of them before you start.
If you use Dropbox, OneDrive, Google Drive or any other form of cloud storage, make sure your data is in sync before you start the process of reversing an upgrade. It's easy to forget that the files that live in your Dropbox folder, or example, are local files and that while synchronisation is frequent, the loss of an internet connection will prevent it and you could have files in your local folder that haven't yet been copied to the cloud.
Clicking on the cloud service's logo in your menu bar should tell you whether synchronisation completed successfully and files are up to date.
If you use Gmail, iCloud mail or any other IMAP server for your email, make sure it's up to date and any drafts you've composed recently have been synchronised. If you use a POP3 account you'll have to manually back up the mail database and restore it after you reverse the upgrade. Or, if you only have a few messages you need to keep, forward them to a Gmail account - you could set one up especially for that purpose.