Catalina update failled mid-way and is stuck due to lack of available disk space. Booted from network drive and deleted files but this only increases purgeable storage and not free disk space. How to turn this purgeable storage into free storage while booted from network drive.


Here's what solved this for me:

  1. Reboot and press Command + R to go into recovery boot mode.
  2. Restore a local Time Machine backup.
  3. Reboot after that's done.
  4. Free up more disk space before you attempt to run the upgrade again.

I didn't expect to a have local Time Machine backup, but in fact there were several.

Hope this helps you.

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The purgeable storage is stored in a local snapshot. Apparently you can use the tmutil in terminal to delete these. Not sure how exactly but will update later today after speaking with the genius who fixed my mac.

Update: This is what was explained to me:

  1. List IDs of local snapshots: tmutil listlocalsnapshots /Volumes
  2. Delete local snapshots: tmutil deletelocalsnapshots [date part of ID]
  3. Repeat for all snapshots.

Haven't tested so try at your own risk. Let me know if it works. Worked for me but wasn't there went the steps were preformed.

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  • Any word on the final usage of that command? – Mosselman Oct 9 '19 at 16:32
  • @mosselman Updated answer. – lcharbon Oct 9 '19 at 20:47
  • thanks for the update. I went another route as you can see in my question-thread – Mosselman Oct 10 '19 at 8:13
  • This answer is describe in more detail at macworld.com/article/3260635/…. It worked for me to get purgeable space back. – Andrew Swift Nov 13 '19 at 5:40

macOS High Sierra (10.13) or later have an APFS file system which does disk state snapshots which are accessible as Time Machine backup.

That means what in case of restart loop because of lack of free space you need to boot into recovery mode by holding Cmd + R right after machine starts, and go into Restore from Time Machine Backup there: you will have local time machine backups and will be able to restore system to its state just before the upgrade.

You don't need an external disk with Time Machine copy to do that, APFS does this for you automatically.

Kudos to @Tobias for his answer, mine has just a little more technical details on why it works.

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