How to restore a Mac from a backup, start to finish

Before you touch anything

• Stop writing to the failing disk. If the Mac still boots and the problem is data loss, with the hardware fine, every further write reduces what can be recovered. Shut it down.
• Find your keys. Your account password, your recovery key if the backup is encrypted, and your Apple Account credentials. A recovery that begins with a password hunt goes badly.
• Do not overwrite the backup. Whatever else happens, the backup is now the only copy. Do not run a fresh backup job "to be safe": that is how a good backup gets replaced with a backup of a broken machine.

Step one: macOS

Apple silicon: shut down, then hold the power button until "Loading startup options" appears. Choose Options, then Continue.

Intel: hold Command and R at the chime.

From Recovery you can use Disk Utility to erase the drive, and then Reinstall macOS, which downloads it from Apple. Expect the download to be the slowest part of the whole day.

Step two: your account

Setup Assistant asks you to create a user. Use the same short account name you had before if you can remember it, because file ownership in the backup refers to it and matching saves you a permissions detour.

If you are restoring from Time Machine, this is where you say so. Migration Assistant appears during setup and offers to bring your files, applications and settings across in one step. That is the smoothest path available on a Mac and it is worth taking when it is an option.

Step three: your files

From Time Machine, after setup: open Migration Assistant from Applications, Utilities, and point it at the backup disk. Same operation, run later.

From a folder-based backup: restore into a scratch folder first, look at what came back, then move it into place. Restoring directly over a home folder that already has files in it is how people end up unable to tell what came from where.

From a Copy Shelter backup: open the app, choose the destination, and restore. If the Mac that made the backup is gone, csctl reads the repository on any Mac with nothing but the drive and your recovery key. It is free, it needs no installation, and it does not care whether you have a license.

Step four: everything that is not a file

• Applications. App Store apps redownload from your account. Others come from wherever you purchased them. A list of what you had installed turns this into twenty minutes. Without one it is two weeks of remembering.
• Passwords. The login keychain comes back with your home folder and unlocks with your account password.
• Licenses. Copy Shelter's own key is in the email you were sent. Most other apps are the same, so search your mail before assuming anything is lost.

The four things that go wrong

1. The recovery key was on the Mac. An encrypted backup and a key stored only on the machine that died is a locked box with the key inside it. Keep the key somewhere else, on paper if necessary.
2. The backup was three months old. The job stopped and nothing said so. This is the most common failure of all, and it is why a tool that speaks up after a week without a successful backup is worth more than one with more features.
3. The backup does not restore. It was written and never read back. Check it before you need it.
4. Hidden files were skipped. Application settings live in ~/Library. A backup that quietly skipped hidden files gives you your documents and none of your configuration.

Common questions

Can I restore to a different Mac?

Yes. Migration Assistant and any folder-based restore both work onto a new machine. Applications built only for Intel may need Rosetta on Apple silicon, which macOS offers to install the first time one runs.

Can I restore just one file?

From Time Machine, enter it from the menu bar and browse back through time. From Copy Shelter, browse the snapshot and restore the one file. From a plain rsync mirror, only if the file still exists in the mirror, which it will not if the mirror has run since you lost it.

How long does it take?

Usually an hour or two, and mostly waiting: the macOS download, then copying your data at whatever your disk or network manages. Plan on an afternoon.

Do I need the internet?

For the macOS install, yes: Recovery downloads it from Apple. For the restore itself, only if your backup is in the cloud. A Copy Shelter backup on a local drive restores with no connection at all, because licenses are verified offline.

What if I have forgotten my recovery key?

Your passphrase opens the same backup, so the key is what you reach for when the passphrase has gone. If both are gone the backup cannot be opened, by you or by anyone, and that is true of every properly encrypted backup. It is the one failure with no fix, which is why the app shows the key once, offers to save it to a file, and says where not to keep it.

Read this before the day you need it, and restore one real file into a scratch folder while nothing is wrong.

Related guides

• How to check a backup is actually readable
• Time Machine says it cannot verify your backups
• Your backup stopped running, and nothing said so
• How to back up a Mac to an external drive
• Backing up a Mac with rsync