Protect your Time Machine backup with encryption

Why it happens

A backup drive holds a copy of almost everything on your Mac. Without encryption, anyone who plugs it into another Mac can open your files. Time Machine asks about encryption when you first add a disk, so setup is the moment to switch it on.

How to fix it

1. Plug in the drive you want to use for backups.

2. Open System Settings, click General, then Time Machine, and click Add Backup Disk.

   macOS 26 Tahoe General›Time Machine›Add Backup Disk

   macOS 27 Golden Gate General›Time Machine›Add Backup Disk…

3. Choose your drive and click Set Up Disk. In the next window, turn on Encrypt Backup.

   macOS 26 Tahoe General›Time Machine›Add Backup Disk›Encrypt Backup

   macOS 27 Golden Gate General›Time Machine›Add Backup Disk…›Encrypt Backup

4. Type a password twice and add a hint that only you would understand, then click Done.

5. Write the password down somewhere safe or save it in the Passwords app. Nobody, Apple included, can open the backup without it.

6. Let the first backup run. It can take a few hours, and your Mac encrypts everything as it goes.

On macOS 27 the button reads Add Backup Disk… with three dots. Everything else is the same as on macOS 26.

Still not fixed?

1. Already backing up to a drive without encryption? Remove that drive in Time Machine settings, then add it again with Encrypt Backup turned on. Read the message your Mac shows before you agree, because it may need to erase the drive first.

2. If Time Machine says the disk must be erased, everything on that drive is deleted, old backups included. Copy off anything else you need from it first.

3. Forgot the backup password? There's no way around it. Try your hint and check the Passwords app. If it's truly gone, you'll need to erase the drive and start a fresh backup.

4. If the drive doesn't appear in the list, try another cable or port and make sure it shows up in Finder.

5. If setup fails with an error every time, even with another cable, contact Apple Support. If no Mac can see the drive at all, it may be faulty and need replacing.