Time Machine is supposed to be your safety net, so it’s a nasty surprise when your Mac has failed and the backup won’t cooperate. Maybe the backup disk doesn’t show up in Migration Assistant, or macOS says it can’t find it. Maybe you’ve been told Time Machine must create a new backup. Your backup may well be intact, but a wrong click at this point can erase it. Here’s what these problems usually mean and what to do before you touch anything.
Common Time Machine problems
- “Time Machine couldn’t complete the backup.” The backup was interrupted or the disk couldn’t be written to. Sometimes this is temporary, but repeated failures can mean the disk is going bad.
- The backup disk isn’t available or can’t be found. The Mac can’t see the disk. The cause could be the cable, the port, the disk’s enclosure or the disk itself.
- “Time Machine must create a new backup.” This is common with backups stored on a network drive or NAS. It means a verification check failed on the backup. Your existing history may still be readable, but starting a new backup can replace it.
- The disk appears, but your backups aren’t listed. The file system or the backup structure may be damaged, or you may be looking at the wrong volume.
- The restore starts and then stalls or fails. A restore that stops at the same point each time often indicates bad sectors on the disk.
Safe checks to try first
- Try another cable and a different port, and connect the disk directly to the Mac, not through a hub. If it’s a desktop drive, confirm that its power supply is working.
- Try the disk on a second Mac if you have one. Just connect it and see whether it mounts.
- Open Disk Utility, choose Show All Devices from the View menu, and see whether the disk is listed with the correct size.
- If the backup is on a NAS, confirm that the NAS itself is healthy and that you can log in to it. A warning on the NAS is the first thing to deal with.
- If your Mac still works, check whether it has local snapshots. Time Machine can keep recent snapshots on the internal drive, so some recent versions of your files may be available even when the backup disk isn’t connected.
If the disk mounts and you can see your backups, restore the most important files first. You can always go back for the rest. Copying your irreplaceable folders before attempting a full system restore is a safer order than the other way around.
What not to click
- Don’t choose Start New Backup if the old backup is your only copy of something. Save what you can first. Time Machine may remove the existing backup when it starts again.
- Don’t erase or reformat the disk. macOS may offer to initialize a disk it can’t read. Click Ignore or Eject.
- Don’t set up your replacement Mac to back up to the same disk until your old data is safe. Time Machine deletes the oldest backups when it needs space, and that can include the files you’re trying to save.
- Don’t run First Aid over and over. Running it once on a healthy disk is reasonable. If the disk is making noises, is very slow, or First Aid reports errors it can’t repair, stop. It writes to the disk, and repeated attempts put more strain on failing hardware.
- Don’t use third-party repair tools on the backup volume. Time Machine volumes have an unusual structure, and automated repairs can make things worse.
Encrypted backups
If you chose to encrypt your Time Machine backup, you’ll need that password to get at the data. There’s no way around this for anyone, including a recovery lab, so look for it now. It may be stored in your password manager, or in the keychain of a Mac that used the backup. When you contact a recovery company, tell them that the backup was encrypted and make sure you have the password.
When the backup disk itself has failed
Backup disks often fail at the worst moment. They’re usually consumer external drives that have been running for years, and a restore puts them under a heavy, sustained load they may never have seen before. If the disk clicks, disappears partway through a restore, or won’t mount on any Mac, power it down. If your Mac has failed too, this backup may be the only copy of your data, so it’s not the time to experiment.
When we receive a failing drive, an engineer evaluates it and gives you a fixed quote. Recovery starts only when you approve it, and we work from a copy of the drive. See our Mac data recovery and external hard drive recovery pages for more, or our NAS data recovery page if your backups were stored on a network drive.
Once you have your data back
A single Time Machine disk is one copy in one place. Keep a second backup, on another drive or in a cloud service, and try restoring a file now and then so you know that it works.
Time Machine backup won’t restore?
Stop, eject the disk and leave it unplugged. Call Data Retrieval at (213) 986-4855. We serve Los Angeles, the Inland Empire and Ventura County, and we accept mail-in drives from anywhere in the US.