Got an old Mac and want to reinstall macOS? Maybe you want to roll back your Mac to an earlier version of macOS than the one you currently have installed? Here’s how you downgrade macOS to an older version.
While the process is pretty straightforward, getting your hands on older releases of macOS isn’t so easy.
Before You Start
It’s important to understand that not all versions of macOS (or Mac OS X) work with all hardware configurations. It’s common knowledge that new macOS releases often drop support for older hardware, but the same is true for newer Mac models and older software, too.
For example, you cannot install any version of macOS prior to Big Sur (released in 2020) on a Mac with an Apple Silicon chip, including the M1. Older versions were written for Intel chips, which use the x86_64 instruction set, while the newer Apple Silicon chips use the ARM instruction set.
Your Mac’s “earliest” supported version of macOS is the one that it came with. If you’re not sure what your Mac came with, head to Apple Support and search for your exact model. You can find out which Mac you have by clicking on the Apple logo in the top-left corner and selecting “About This Mac” to see the name and year of release.
If you’re willing, you can install newer versions of macOS than your Mac supports with tools like Patched Sur. After trying this, you might come to the conclusion that newer releases perform too poorly on your hardware, at which point, you’ll need to roll back.
This guide can help you roll back to almost any version of macOS. If you do decide to try a new version of macOS and you’re reliant on Time Machine for your backups, resist backing up with Time Machine until you’re sure that it’s where you want to stay.
Older versions of macOS might experience problems restoring from Time Machine backups made on subsequent releases. For example, trying to restore a Time Machine backup made in Big Sur (released in 2020) in macOS Catalina (released in 2019) could prove difficult.
You can get around this by using a third-party backup tool like Carbon Copy Cloner or ChronoSync. As a last resort, you could manually back up your important documents, libraries, and so on to an external drive. We’d recommend test-driving any experimental macOS installations for a while before you commit.
Where to Download Older Versions of macOS
You can download most older versions of macOS using the Mac App Store or direct links to Apple’s website. Unfortunately, Apple doesn’t index the Mac App Store entries so that you can search for them in the app. To get them, you’ll need to follow direct links, which we’ve listed below.
Note: If you have trouble getting these links to work, first, make sure that you’re using Safari, and then try closing the Mac App Store and clicking on the link again.
Mac App Store Links for Older macOS Downloads
Once any of these downloads finishes, do not open the installer to begin the installation. Leave the installation app in your Applications folder.
- macOS Big Sur (2020)
- macOS Catalina (2019)
- macOS Mojave (2018)
- macOS High Sierra (2017)
Direct Disk Image Links for Older macOS Downloads
Once any of these downloads are complete, mount the .DMG file and run the .PKG installer within. This will put an installation app in your Applications folder, which you should leave there.
- macOS Sierra (2016)
- Mac OS X El Capitan (2015)
- Mac OS X Yosemite (2014)
Get Even Older Versions of OS X
If you have a valid Apple Developer account, you might be able to download older versions from developer.apple.com/downloads. Non-developers can buy OS X Mountain Lion ($19.99) and OS X Lion ($19.99) from Apple directly. Apple will email you an unlock code, which you can redeem in the Mac App Store.
There might be old copies of Lion, Mountain Lion, and even Snow Leopard for sale on sites like eBay.
Some websites might offer old versions of OS X for download, but we recommend avoiding them. First, the installer might contain malware. Second, there are legal concerns: OS X is still copyrighted software. Even if you own a license, you might not be able to legally download it in your jurisdiction. If you can, you might not be able to legally use BitTorrent to download it, as your BitTorrent client will be uploading parts of OS X to other people during the download process.
Reinstalling an Older Version of macOS
Creating a bootable USB stick is necessary to install an older version of macOS. You can use this drive multiple times in different machines, throw it in a drawer for next time, or erase it when you’re done and make a new one when it’s time to reinstall again.
Prepare Your USB Drive
Apple recommends a USB drive that’s formatted as Mac OS Extended, with 14GB of free space for the latest versions of macOS. We’ve used 8GB drives in the past to install Catalina and earlier, so your mileage might vary.
To format your drive, connect it to your Mac, and then launch Disk Utility (You can do this by using Spotlight or by finding the app in your Applications > Utilities folder.). Locate the drive in the sidebar, click on it, and then click “Erase” and give it a name. In the drop-down box, select “Mac OS Extended (Journaled),” and then click “Erase” to start the process.
Create a Bootable USB in Terminal
We’ll be using Terminal to create the USB drive, so launch it via Spotlight or locate the app in your Applications > Utilities folder. You can use a single command to create your installation medium, but this differs depending on which version of macOS you’re trying to install.
This assumes that you’re installing Big Sur, that your drive is labeled “macos_installer,” and that you have the relevant macOS installer in your Applications folder:
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/macos_installer
You can change various parts of this command to suit your own circumstances, with the main one being the name of the installer. Be aware that any spaces will need to be preceded by a backslash. For example, “Install macOS High Sierra.app” would become
Install\ macOS\ High\ Sierra.app in this context.
Here’s another example that creates a macOS High Sierra install USB on a drive named “MacOS Installer”:
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MacOS\ Installer
You can run the
ls command to list all connected volumes, which will include your USB installation medium in case you need to check the label.
Once you hit Enter, you’ll need to enter your admin password to approve the command, and then hit “Y” on your keyboard to confirm that you’re OK with the contents of the USB drive being overwritten.
Install macOS from Scratch
Once your installation files have been copied, it’s time to install macOS from scratch. To ensure that everything goes smoothly, we’ll take the extra step of deleting your existing partition before installing macOS.
First, insert your USB drive and turn off your Mac. The next instruction will differ depending on which type of Mac you have (Here’s how to tell.). They are as follows:
- Apple Silicon (M1 chip and newer): Press and hold the power button until you see the startup options window, and then click on the USB volume that you created earlier and click Continue.
- Intel-powered Mac: Press and hold Option (Alt) as you turn your Mac on. Release when you see a list of bootable volumes, select the USB stick that you created, and click on the upward-pointing arrow.
Once macOS loads (You might need to select a language first.), click on Utilities > Disk Utility. Select your drive (usually labeled as “Macintosh HD”) in the sidebar, and then click “Erase.”
Warning: The contents of your Mac’s system volume will be erased in the next step, so make sure that you’ve backed up any data that you don’t want to lose.
If you’re installing macOS Sierra or later, choose “APFS.” Otherwise, you’ll need to format to “Mac OS Extended (Journaled)” for El Capitan and earlier. When you’re sure about your decision, click “Erase” and confirm.
Finally, quit Disk Utility and select “Reinstall macOS” or “Install macOS” (or Mac OS X, for older versions) from the macOS Utilities window. Follow the rest of the prompts to finish the installation.
Perfect for Older Apple Computers
You might be interested in doing this if you have an older Mac that isn’t compatible with the latest version of macOS but that might still benefit from a squeaky clean installation. This is one of the few things that you can try to improve performance on an old Mac.
Finally, if this worked out for you, consider keeping a copy of your preferred retired version of macOS on a spare drive, just in case it’s hard to find by the next time you try this.
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