How to Downgrade MacOS High Sierra Beta to Sierra or El Capitan with Time Machine
A fair number of Mac have installed MacOS High Sierra public beta or the developer releases to test out the new features, but it’s not uncommon to test out beta system software and then decide to downgrade back to a stable release.
This tutorial will show you how to downgrade from MacOS High Sierra (10.13) beta back to MacOS Sierra (10.12.x) or OS X El Capitan (10.11.x) by using Time Machine to restore a previously made backup. Using a prior Time Machine backup offers the simplest way to downgrade MacOS High Sierra.
Important: If you do not have a Time Machine backup made from a prior install of MacOS Sierra or El Capitan, this approach will not work to downgrade because you will not have a Time Machine backup to restore from. Do not proceed without a Time Machine backup you can use to restore.
Warning: You will be formatting and erasing the hard drive in this process, this will destroy all files and data on the drive. Do not proceed without having a backup of your files and data. Failure to do so will result in permanent data loss.
Downgrading from MacOS High Sierra Beta
Before anything else, confirm that you have a Time Machine backup to restore to, and that you have a current backup of your important files and data.
- Connect the Time Machine volume to the Mac if you have not done so already
- Reboot the Mac and hold down Command + R keys together to boot into Recovery Mode
- At the “macOS Utilities” screen, choose “Disk Utility”
- Choose the partition or hard drive with MacOS High Sierra installed on it, then choose the “Erase” button
- Give the drive a new name and then select “Mac OS Extended (Journaled)” as the file system format, then click “Erase” – THIS DESTROYS ALL DATA ON THE DRIVE, DO NOT PROCEED WITHOUT A BACKUP
- After the drive has finished formatting, quit out of Disk Utility to return to the ‘macOS Utilities’ screen and now choose “Restore from Time Machine Backup”
- Choose your Time Machine volume as the backup source then click Continue
- At the “Select a Backup” screen, select the most recent backup available that corresponds to the version of MacOS you want to restore – remember that Sierra is “10.12” and El Capitan is “10.11” whereas High Sierra is “10.13” then choose Continue
- Select the destination to restore the Time Machine backup to, this will be the partition or drive you formatted in step 5, then choose “Restore” and confirm
- Let the restore process complete, this can take a while depending on the size of the hard drive and backup
When finished, the Mac will reboot itself automatically and boot back into the MacOS version you restored to. MacOS High Sierra will have been removed in the erase and format process, and the prior macOS release will have been installed via the Time Machine restore process.
* Typically you can downgrade by simply restoring from a prior Time Machine backup to downgrade, but because MacOS High Sierra wants to use APFS file system (as opposed to HFS of prior Mac OS releases) you will want to format the hard drive back to the prior file system. That is not the case if you did not update to APFS or when downgrading from Sierra to El Capitan for example.
If you’re downgrading from macOS High Sierra beta because you found it to be unstable or have performance issues, you’ll likely want to wait until the final version of macOS High Sierra is available before installing it again – the final release is set for launch this fall.
Do you have any questions or comments about downgrading from macOS High Sierra beta back to a stable build of Sierra or El Capitan? Let us know in the comments below.