So Apple has shipped the next major operating system, and you're excited to upgrade! But are you ready? OS upgrades offer the thrill of new features, better performance and bug fixes, but they can come at a price — your time and potentially your productivity. If you upgrade your OS only to discover that a critical third-party application or peripheral doesn't work right, you could be really lost when you discover that it's impossible to downgrade to a previous OS. Unless, that is, you have a CCC backup of your Mac made before you upgrade.
Major system upgrades are often disruptive, so we have always recommended a very conservative approach to applying them. Consider the following:
- Is the upgrade required for my Mac?
- Does the upgrade offer any compelling features?
- Will this upgrade improve the performance of my Mac, or degrade performance?
- Does the upgrade fix a problem that is preventing me from effectively using my Mac?
- What software will no longer work after applying the upgrade?
- Does the application of this upgrade to my aging Mac hasten its obsolescence?
If the upgrade turns out poorly and you have to downgrade, you certainly may downgrade using a CCC backup from an earlier OS. These sorts of procedures require time and effort, though, so you should weigh that potential hassle against the potential gain of the OS upgrade.
Lastly, we recommend that any users that rely heavily upon the availability of their Mac for work or other productivity consider waiting for several OS updates before making a major upgrade. The early releases are exciting, but that excitement involves risk. Early adopters inevitably find some shortcomings and bugs which are resolved in minor OS updates.
Make a CCC backup before upgrading
- Get a backup disk. If you would like a recommendation, we offer some here in CCC's documentation.
- Prepare your backup volume for the backup.
- Download CCC and open it.
- Choose your startup disk in the Source selector.
- Choose your backup volume in the Destination selector.
- Intel Mac running Big Sur+ (optional)†: Click on the Destination selector and choose "Legacy Bootable Backup Assistant", then click the button to allow CCC to erase the destination.
- Click the Start button.
- Detach your backup disk from your Mac and set it aside. Until you are ready to commit to the newer OS, you don't want the backup disk to be upgraded automatically by a scheduled backup task.
† Should I make a bootable backup?
Downgrading from a bootable backup requires fewer steps, but the reliability of Apple's External Boot solution has waned in the past several years. Having a bootable backup gives you an additional recovery option, but you can downgrade your Mac from a CCC backup whether that backup is bootable or not. The important thing to do is make the backup before you upgrade, and understand your downgrade options before proceeding with the upgrade. Apple Silicon Macs: You can make a bootable backup on these Macs as well, but the Mac's behavior while attempting to boot from an external device (backup or fresh macOS install) is pretty frustrating after you have erased the internal disk. We recommend the standard recovery procedure to downgrade an Apple Silicon Mac.
Upgrade to the new OS
Download the newest OS from the Mac App Store and apply the upgrade.
Take some time to run the applications that are most important to you. Keep in mind that when you open an Apple application (e.g. Mail, Photos, etc.) on the newer OS, those applications will immediately and irreversibly upgrade the user data for those applications. If you decide later that you want to downgrade, you cannot simply reinstall Big Sur (for example), then go about your day with the upgraded user data; the Big Sur versions of those Apple applications can't use the upgraded data from Monterey. If you need to downgrade to a previous OS, it is imperative that you have a CCC backup of your Mac as it was prior to the upgrade.
If, after a week or so you decide that everything is copacetic and you are ready to commit to the new operating system, attach your backup disk to your Mac, open CCC and re-run your backup task with the same settings. This is an important step — once the backup task has completed, you will no longer be able to use the backup to downgrade to the previous OS.
Note: If you created or modified any documents while the system was running the newer operating system, the older versions of your files will be restored. Unfortunately, your personal data created by Apple applications (e.g. Mail, Photos, etc.) while using the newer OS will be incompatible with an older OS, so it is not possible to restore changes that were made while you were using the newer OS.
- Download the macOS installer for the OS that you would like to downgrade to: [Catalina], [Big Sur]. Use Safari to open the link if you're not redirected to the App Store application.
- Create a macOS Installer device: How to create a bootable installer for macOS.
- Restart your Mac while holding down the Option key (Intel Macs) or the Power button (Apple Silicon Macs).
- Select the installer device as the startup disk and proceed with startup.
- Open Disk Utility.
- Choose "Show all devices" from the View menu.
- Select the parent-level device of your Mac's internal storage in the sidebar.
- Click the Erase button in the toolbar. Erase the internal disk with the APFS format.
- [Intel Macs]: Quit Disk Utility.
- [Apple Silicon Macs]: Proceed when prompted to "fully erase the Mac".
- [Apple Silicon Macs]: The system will automatically reboot into Recovery Mode and prompt you to activate the Mac. Connect to WiFi or ethernet; the Mac will activate itself.
- [Apple Silicon Macs]: Shutdown, then boot the system while holding down the Power button.
- [Apple Silicon Macs]: Select the installer device as the startup disk and proceed with startup.
- Choose the option to reinstall macOS, then proceed to reinstall macOS on the internal disk of your Mac.
- When prompted during Setup Assistant, choose the option to migrate data from your CCC backup volume. Proceed as directed by Migration Assistant.
If your CCC backup is bootable, then do the following to restore everything back from your last pre-upgrade backup. We do not recommend using this procedure for Apple Silicon Macs, please use the procedure above instead.
- Restart your Mac while holding down the Option key.
- Attach your CCC backup disk to your Mac (do not attach your backup disk prior to the first step).
- Select your CCC bootable backup volume in the Startup Manager and proceed with startup.
- Open Disk Utility
- Unmount the original (upgraded) startup disk.
- Choose "Show all devices" from the View menu.
- Select the whole disk device that contains your original startup disk — the parent of the "Macintosh HD" volume.
- Click the Erase button in Disk Utility's toolbar. Erase the internal disk with the APFS format.
- Open CCC and click the Restore button in the toolbar to create a new Restore task.
- Select your backup volume from the source selector.
- Select your original (now empty) internal volume from the destination selector.
- Big Sur (and later): Click on the Destination selector again and choose "Legacy Bootable Backup Assistant", then click the button to allow CCC to erase the destination.
- Click the Start button.
- When the restore process has completed, restart your Mac while holding down the Option key.
- Select the restored volume in the Startup Manager.
- When the system has rebooted, reset the startup disk selection in the Startup Disk Preference Pane.
Downgrading without a pre-upgrade CCC backup is not a simple task, and may not produce the result you're hoping for. There are some items that the older system applications can't read, e.g. Apple Mail, Photos – basically all of the Apple applications won't be able to use the upgraded data stores. If you're staring at a clean install of the older OS, your best option is to try restoring just your home folder. This is not a configuration that we can offer support for (the supported configuration requires having a pre-upgrade CCC backup), but you can do the following in CCC to restore your home folder:
- Downgrade your Mac's OS using the procedure described above
- Close all applications and all Finder windows
- Open CCC and create a new task
- Drag your home folder from the backup disk onto CCC's Source selector
- Drag your home folder from the current startup disk to CCC's Destination selector
- Click the Advanced Settings button
- In the "File Copying Settings" tab, check the box next to Don't preserve permissions (this will avoid any ownership issues that would arise from your account having a different numeric ID on the old and new system)
- Click the Start button
If you have applications that you want to restore, we recommend restoring them via drag and drop in the Finder, or reinstall them from their installers.
Keep in mind that this is going to replace anything that you currently have in your home folder. If you have already restored items manually, this will undo that, and you may want to consider manually restoring files via drag and drop instead.
- Everything you need to know about CCC and APFS
- Downgrading from macOS Catalina to macOS Mojave
- Preparing your backup volume for an installation of macOS
- Working with Disk Utility to prepare your CCC backup disk
- Testing your CCC backup
We're here to help
If you get stuck or need some advice, you can get help right from within CCC. Choose "Ask a question" from CCC's Help menu to pose a question to our Help Desk.