Can I back up one computer and use the clone to restore another computer?

This documentation is for an older version of CCC. You can find the latest version here.
Last updated on December 15, 2020

Often, the answer is probably yes. However, there are some caveats.

Don't install older versions of macOS than what your computer shipped with

When you get a brand new Mac from Apple, it has a specific version of macOS installed on it, and further, a build that is specific to that exact model of Mac. If you install an older version or build of the OS, for example by cloning your older Mac to it, then it may behave unexpectedly, or it may not boot at all. If your new Mac is brand new, use Migration Assistant to migrate your data to your new Mac.

If your new Mac is just different, but not really hot off the production lines, then cloning another Mac to the new Mac may work fine. When cloning your source Mac to your new Mac, be sure that your source Mac has been updated to at least one later release than what came on the newer Mac. For example, if your newer Mac came with 10.12.4, update your source Mac to 10.12.5 before migrating. If such an update is not available, use the Migration Assistant instead.

T2 and Apple Silicon Macs have "personalized" operating systems

When macOS is installed onto a T2 or Apple Silicon Mac, the macOS Installer signs some of the startup resources with a code signature that is unique to your Mac. If you attempt to boot your Mac from the backup of some other Mac, your Mac will refuse to boot from that volume, claiming:

A software update is required to use this startup disk. You can update now or select another startup disk.

The "update" involves downloading system resources and then personalizing the backup volume's OS to the current Mac. This requires an Internet connection. Typically the application of that update works and the backup volume is then bootable, but various factors can cause that to fail. After confirming that the version of the operating system is compatible with the Mac you're trying to boot, there are two options to make this work:

T2 Mac

  • Hold down Command+R to boot the Mac into Recovery Mode and change the Secure Boot setting to Medium Security, then proceed to attempt to boot from the backup volume or
  • Hold down the T key on startup to boot the Mac into Target Disk Mode, attach the Mac and the backup disk to another Mac, then restore the backup directly to the TDM Mac's internal storage. CCC will ask macOS to personalize the destination Mac. This procedure requires macOS Catalina or later and an Internet connection.

Apple Silicon Mac

Hold down the Power button on startup, select "Options", then press the Continue button. Then:

  • Choose "Startup Security Utility" from the Utilities menu, then change the Security Policy to Reduced Security, then proceed to attempt to boot from the backup volume or
  • Choose, "Share Disk..." from the Utilities menu, select a volume to share, then click the "Start Sharing" button. Attach the backup disk directly to another Mac, attach the Sharing Mac to the other Mac via USB or Thunderbolt, then restore the backup directly to the Sharing Mac's shared disk. CCC will ask macOS to personalize the destination Mac. This procedure requires macOS Catalina or later and an Internet connection.

Do not attempt to restore the backup of an Intel Mac to an M1 Mac. If you're attempting to migrate data from an older Mac to a newer Mac, you should use Migration Assistant.

Some of your preferences on macOS are considered "host-specific"

Preferences such as these will be ignored if you boot another machine from your cloned operating system and data. For example, the screen saver preferences are host-specific — if you boot another machine from your bootable clone and the screen saver kicks in, you will notice that it has reverted to default settings. Do not fear that you have lost any data, your original preferences will be "restored" when you boot again from your original Mac. To learn exactly what preferences are host-specific, hold down the Option key and choose Library from the Finder's go menu, then navigate to Library > Preferences > ByHost.

Network settings may not be respected on another Macintosh

In addition to application-specific preference files, the network configuration of one Mac may not be accepted by another Mac. macOS network settings are stored in /Library/Preferences/System Configuration/preferences.plist, and CCC will copy that file unless you explicitly exclude it. Sometimes a Mac will respect the settings configuration file from another Mac, but often there are enough differences in the networking hardware configuration that macOS decides to ignore the contents of that file.

Some applications may behave differently when you open them on another Mac

This section of CCC's documentation highlights some of the affected applications that we're aware of.

The macOS Installer applies a firmware upgrade

Older Macs won't recognize APFS volumes as bootable devices until the macOS Installer has applied a firmware upgrade. If you're planning to clone High Sierra or later onto another Mac, you must have used the macOS Installer at least once on that system before you will be successful cloning the newer OS to that Mac.

So how can I find out if it will actually work?

Determining whether this type of clone will work for you is really easy — simply boot the destination Mac from your CCC backup of the source Mac:

  1. Attach the CCC backup of the source Mac to the destination Mac with a Thunderbolt or USB cable.
  2. On the destination Mac, open the Startup Disk preference pane in the System Preferences application and set the source Mac's backup volume as the startup disk, then click the Restart button.

If the destination Mac successfully booted from the source Mac's installation of macOS, then it works! Open CCC, then clone the source Mac's disk to the destination Mac's internal hard drive. If the destination Mac could not boot from the source Mac's installation of macOS, use the Migration Assistant to transfer your user data and applications instead.

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