OS updates are a good thing because it usually signifies security improvements, new features, bug fixes, and all that jazz. Apple has typically announced a new major macOS update once a year (not counting smaller updates in between), but sometimes these updates aren’t necessarily a good thing.

For example, those on older hardware might find that while they are eligible for the update, their computer might end up feeling sluggish and slow after updating. Or maybe there are changes made to the UI that some users just aren’t a fan of, or maybe there could be some major bugs or app incompatibility issues with the new build.

Thankfully though, if you want to go back to the previous version of macOS, or an even older version of macOS, it is possible, and here’s how to do that.

Things You Should Know

  • If you happen to own an M1 or any M-series chipset, old versions of macOS will be incompatible as they were written for Intel’s x86 platform in mind
  • The oldest version of macOS you can downgrade to will be the version your Mac came with, so for example if you bought an iMac that came with OS X Lion, in theory that would be the earliest version you can reinstall
  • Restoring Time Machine backups could be tricky if you’re trying to restore a backup made on a newer version on an older version of macOS (for example restoring a backup made on macOS High Sierra on OS X El Capitan)

Downloading macOS

If you’ve decided to download an older version of macOS, these are the options that you’ll be able to find from the App Store:

Preparing Your USB Drive

After you’ve downloaded the version of macOS you want to downgrade to, you might be tempted to just click on the installer and let the installation begin, but unfortunately it’s not that simple as you will need to create a bootable USB drive.

Before you proceed, make sure that you have all your important files backed up to an external drive or to the cloud so that you don’t lose those files in case something goes wrong during the installation process.

Apple recommends that users have a USB drive that has at least 14GB of free space and that it has been formatted as Mac OS Extended. To do this:

  1. Connect your USB drive to your Mac
  2. Launch Disk Utility
  3. Click on the drive on the sidebar to the left and then click Erase
  4. Give the drive a name, select Mac OS Extended (Journaled) under Format
  5. Click Erase
  6. Give it a minute or two and it should be done

Keep in mind that this essentially wipes your USB drive of all data, so make sure that the USB drive you plan to use doesn’t have anything important on it.

Create A Bootable USB

Now that your USB drive has been formatted properly, you’ll now need to make sure it is bootable.

  1. Connect your USB drive to your Mac
  2. Open the Terminal application
  3. Type in the command lines below (as shown on Apple’s support page) depending on which version of macOS you’re trying to install. Also remember to change MyVolume to the name of the USB drive you’re using:
    • Big Sur – sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume
    • Catalina – sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume
    • Mojave – sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume
    • High Sierra – sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume
    • El Capitan – sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume –applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
  4. Once you’ve entered the command line, hit Enter
  5. Enter your admin password if prompted and hit Enter again
  6. Enter Y to confirm you want to erase the USB drive
  7. You’ll be prompted that Terminal wants to access files on the removable volume, click OK to allow
  8. Once Terminal says it’s done, you can quit the app and remove the USB drive

Installing macOS From Scratch

Once all the necessary files have been copied to your USB drive, it’s time to begin the installation. Once again, we’d like to take this opportunity to remind you that you should make sure everything is backed up to an external drive or the cloud before you begin the installation process, just in case something goes wrong and you lose your files.

Also, make sure your computer has access to the internet. According to Apple, the bootable installer doesn’t download macOS from the internet (you already did that previously), but rather it needs an internet connection to get the firmware and information specific to your Mac model.

Now insert your USB drive to your Mac and turn off your computer.

Apple Silicon

  1. Turn on your Mac and continue to hold down the power button until you see the startup options window
  2. Select the drive containing the bootable installer and click Continue
  3. Follow the instructions on the screen to complete the macOS installation


  1. Turn on your Mac and immediately hold the Option (Alt) ⌥ key
  2. Release the key when you see a dark screen that shows your bootable volumes
  3. Select the volume containing the bootable installer and press Enter
  4. Select your language if prompted
  5. Select Install macOS (or Install OS X) from the Utilities window
  6. Click Continue and follow the instructions to complete your macOS installation

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