I am concerned about not being able to use Time Machine to back up my drive. I've been told that was due to my disk being formatted as APFS. What must be done to return my Mac to Mac OS Extended (Journaled) format. Will this solve the sudden stopping of Time Machine? Is there a better way to get Time Machine working on my computer.

I have an older iMac running High Sierra.


The external drive used to store Time Machine backups must be formatted with HFS+, also known as Mac OS Extended (Journaled). If the external drive is formatted with APFS, it cannot be used for storing Time Machine backups.

The internal drive in your Mac used to contain the macOS operating system can be formatted with either APFS or HFS+. Both choices will support backing that computer up with Time Machine.

If your computer was automatically converted to APFS with the upgrade to High Sierra this has nothing to do in itself with your Time Machine problem. Such a system is still supported to be backed up with Time Machine.

If you want to reverse the automatic conversion from HFS+ to APFS, you'll need to backup the system, reformat the computer with HFS+ and then restore from the backup (or reinstall a new macOS operating system if you haven't got any data to save). Unfortunately there's no automatic conversion program from APFS to HFS+.

Note that such a conversion from APFS to HFS+ does not in itself improve your Time Machine situation.

  • The disk were i'm storing time machine bckups is formatted as HFS+. Why did time machine stop?
    – Natsfan
    Apr 2 '19 at 23:34
  • 3
    You'll need to ask that as a seperate question. In order to get it answered, you'll need to include information such as "has it worked before", "what did you do at the time it stopped working", "what kind of error messages do you receive", "what is your Time Machine configuration", etc. There can be many reasons why Time Machine stops working - without information, noone can help you decide which one is the culprit for you. However I can say with certainty that having the boot drive formatted as APFS is not problematic.
    – jksoegaard
    Apr 2 '19 at 23:45

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