Time Machine not working on Apple Mac? Fix Time Machine backups

Make sure Time Machine is working and backing up your Mac

The backup software built into macOS is pretty good and Time Machine is all some people use to safeguard their files. What happens when it goes wrong? Here are some quick and easy fixes for it.

Time Machine is enabled in System Preferences > Time Machine and it is mostly automatic, with few features. Just about the only thing you need to do to get it running on your Apple Mac is to plug in an external drive, HDD or SSD, and click the Select Disk button. Choose a drive for storing backups and that’s it.

Time Machine backup utility in macOS on the Apple Mac computer
Time Machine is one of the easiest backup utilities to use

A big backup drive is best, but it really only needs to have enough space to store your data. If you have a 1 TB drive in your Mac, but only 250 GB of data, you could use a 500 GB USB drive. Time Machine stores multiple versions of files, so it needs a bit more space than is being used by your Mac. About double the space being used should be regarded as the minimum.

Enable Time Machine and you can then forget it. It works automatically in the background without you having to do anything, which is brilliant. It rarely goes wrong, but if problems occur, there are solutions. Let’s take a look at them.

1 Use a supported drive

Plugging in an external USB drive is the easiest and most compatible way to add a destination for Time Machine backups. Do not use a hub, connect the drive directly to the Mac.

Time Machine problems usually only occur when using networked drives, like NAS drives. The destination drive must support Time Machine over SMB. Many NAS drives do, but a few don’t. Check the specifications.

2 Format the drive

New drives or drives used on other computers, such as a Windows PC, may need to be formatted before they can be used as a Time Machine backup destination. If a drive is selected for backups and it is the wrong format, Time Machine should prompt you to format it. However, if you are having problems, it is a good idea to manually format the drive before trying to enable Time Machine.

Formatting a disk using Disk Utility on the Apple Mac computer
Format the disk or partition with APFS for Time Machine

Open Disk Utility, select the drive and click the Erase button. Click the Scheme and select GUID Partition Map if it has not been partitioned. Usually you just need to select a partition and click Erase. Select the APFS format, name the drive or partition and erase it. Afterwards, go to Time Machine and select the drive or partition for backups.

Time Machine can work with other formats, but APFS is the newest and best disk format and is preferred.

3 Repair the disk

Disk problems occasionally arise and the filing system gets in a muddle. This could cause Time Machine to display error messages. It can happen on a drive that has been working fine for months or years. One day there is a glitch and Time Machine stops.

Checking a disk for errors with Disk Utility on an Apple Mac computer
Find and fix disk errors with Disk Utility on the Apple Mac

Open Disk Utility, select the drive or partition that is used for backups and click the First Aid button in the toolbar. Check the drive for errors and if any are found, they will be automatically repaired.

4 Verify backups

Verifying existing backups may help to spot problems or to fix them. Click the Time Machine icon in the menu bar (show it in System Preferences > Time Machine), hold down the Option key and click Verify Backups. If errors are found, repair the disk and try again.

5 Time Machine disk full

Time Machine performs a full backup of everything the first time it is used. This takes a long time and uses a lot of space on in the target disk. Subsequent backups only store files that have changed, so are quicker and require less disk space.

When the disk is full, Time Machine should automatically delete the oldest versions of files. If you edit a file every day, then a new version is stored every day. When the drive is full, the oldest versions will be removed, leaving the most recent one. If you keep your eye on Time Machine status, you may spot it deleting old files.

In some circumstances, the backup disk is full, but Time Machine cannot delete enough old files to make space for new ones and it just stops. There isn’t a lot you can do when this happens. Apple says you should get a new backup disk.

The only other alternative is to format the backup disk and start again. Formatting deletes all your previous backups, which will contain multiple versions of files, but then you can create a new backup and it will use less space. At least initially.

6 Update macOS

Update macOS in System Preferences on the Apple Mac
Mac sure macOS is up to date on your Apple Mac

Time Machine is built into macOS and an update to macOS might include fixes for problems with backups. Go to System Preferences > Software Update and check for macOS updates.

7 Time Machine is slow

There are several possible causes and the first backup Time Machine creates will take a very long time because there is so much to copy. Let it run overnight or when you have a few hours to spare during the day.

If you only plugin the backup drive occasionally, like once a week, there will be a lot to back up. If the backup drive is available all the time, the hourly backups are fast because little has changed since the last backup.

Antivirus software may slow down Time Machine backups because it may check every file read and written. Disable it for the first backup, subsequent ones are quicker anyway. Backups may be paused if the Mac is hot and busy, such as playing games or if a MacBook’s battery level is too low.

8 Preparing backup takes too long

It is normal for Time Machine to take some time to prepare a backup when the backup drive has not been connected for some time. Suppose you go on a trip with a MacBook and it is not plugged into the Time Machine drive for several days, it could take quite a wile to prepare for a backup when you get back home or to the office and plug in the drive. Just be patient.

Antivirus software can interfere with backups. If the antivirus app allows files to be excluded, exclude the Backups.backupdb file on the Time Machine drive. The whole drive could be excluded because it is simply a copy of what is on the Mac’s drive anyway, and that has been checked for malware. It should not get to the Time Machine backups.

9 Can’t find the backup drive

If Time Machine cannot find the backup drive, try turning everything off – Mac and backup drive, then unplug it. Plug it back in and then turn everything back on. See if you can see the drive in Finder. It should appear in the Locations section of the sidebar.

Related articles


Recommended software (affiliate links):

Get the Apple Mac maintenance tool, CleanMyMac X: Uninstall app leftovers, block, remove malware, free disk space, optimize your Mac. Learn more

Keep your Apple Mac fast, clean and organized with MacCleaner Pro. Analyze disk space, clean junk, remove software bloat. Learn more


About Anthony Waddilove 41 Articles
I have been a computer, phone and internet enthusiast for many years. This has enabled me to build up an extensive knowledge about them. I still have a lot to learn, but I am working hard at it!