Video: How to downgrade from macOS High Sierra to Sierra

MacOS High Sierra is Apple's newest operating system for Mac, but some users might have issues with applications or home server setups not working correctly. AppleInsider shows you how to downgrade, if you must.

Assuming you've got a mac older than the iMac Pro that works with macOS 10.12 Sierra, there is a way to revert to the older system.

If you're one of those users having trouble and have decided to go back, the first step is to download the Sierra installer. Apple has a convenient support page, with links on how to download the installer from the Mac App Store.

Once the download is complete, you'll see an error saying that the application is too old to run on your machine. But, we can circumvent this by making an external install drive. First, make a backup of all your data, because the rest of this procedure will erase your system drive. Also, if you're on a MacBook or MacBook Pro, now would be a good time to connect to power.

Insert a USB flash drive. When the USB drive shows up in finder, rename it Sierra. Open the Terminal.

In the terminal window, enter: sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia — volume /Volumes/Sierra and hit enter.

A little lock icon will show up for user password validation — just type in your password to authenticate and hit enter.

You will be asked for permission to erase all the data on the drive. Type the letter y, and hit enter. Terminal should now start copying the boot files to the USB drive.

Once the process is complete, you can close the terminal, and eject the USB drive.

Once your data is backed up, click the Apple icon in the upper left corner of the screen, and select Restart. Hold down Command+R, and keep holding the keys until your computer restarts and a loading bar shows up. After it's finished, click Disk Utility, then continue.

You are about to erase your system drive — make sure you have your backup!

Select your startup disk, which is usually named Macintosh HD. Just formatting the drive won't do, as it will allow only APFS for SSD-based machines.

Instead, hit Cancel and click Partition. Change the format to Mac OS Extended (Journaled), and then click Apply.

Click Partition on the next popup, which will erase all the data on the drive, and warn you accordingly.

When the process is complete, you drive is reformatted to allow a MacOS Sierra installation. Click the Apple icon once again, and Restart the system.

This time, hold the Option button until it restarts to the system selector screen. Plug in your USB installation drive.Once it shows up, click Install MacOS Sierra.

After it loads, click Install MacOS, and continue. Once you've read and agreed to Apple's terms and conditions, click on your main drive. Which we assume is still called Macintosh HD, then click Install.

Continue through all the pop-ups to begin the installation.Once the installation is complete, choose your language, and hit Continue to complete the rest of the installation process.

When complete, open the Mac App Store, and update to the latest macOS Sierra software — just make sure not to accidentally reinstall macOS High Sierra. This won't turn off notifications to upgrade to High Sierra, you'll still get those daily. Fortunately, they can be turned off permanently.

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29 Comments

deminsd 143 comments · 7 Years

About 6 years ago

So now you've got a fresh install of Sierra. What about your apps and data that were supposedly backed up? Would it have been easier if one had a Time Machine backup of Sierra, to have done a restore from that instead?

This just seems like a last ditch effort to get back to Sierra with tons of work involved putting the pieces back together.

vadimyuryev 169 comments · 7 Years

deminsd said:

So now you've got a fresh install of Sierra. What about your apps and data that were supposedly backed up? Would it have been easier if one had a Time Machine backup of Sierra, to have done a restore from that instead?

This just seems like a last ditch effort to get back to Sierra with tons of work involved putting the pieces back together.

Yes you can do the time machine backup from Sierra instead of installing a fresh copy of Sierra.

larz2112 291 comments · 16 Years

deminsd said:

So now you've got a fresh install of Sierra. What about your apps and data that were supposedly backed up? Would it have been easier if one had a Time Machine backup of Sierra, to have done a restore from that instead?

This just seems like a last ditch effort to get back to Sierra with tons of work involved putting the pieces back together.

I may be wrong, but after the clean Sierra install I think you can use Migration Assistant to move just your Applications and User folders from your backup drive back to the system hard drive. Yes, a Time Machine restore might be less of a hassle, but there may be certain circumstances when a clean OS install is necessary, regardless of whether you are downgrading or not.

sziehr 12 comments · 13 Years

so you know it has to be a bad OS update when Apple insider post a way to downgrade.

Apple this is bad.

Mike Wuerthele 6901 comments · 8 Years

sziehr said:

so you know it has to be a bad OS update when Apple insider post a way to downgrade.

Apple this is bad.

It isn't bad. Anybody who says that High Sierra is the worst ever either hasn't been using computers long, or has a very short memory.

We've been asked for this, so we delivered.

There are legitimate reasons to downgrade. Critical peripherals not working after a driver hasn't been updated, expensive vertical market software breaking, that kind of thing. Everybody else should upgrade, if they can.