I have a MacBook Air running macOS Catalina 10.15, upgraded from an older version.

There's only a few 10s of megabytes free on the disk, but deleting files and emptying the trash doesn't change the amount of free space.

I've tried:

  • looking for time machine snapshots that can be deleted, but there do not seem to be any (tmutil listlocalsnapshots /System/Volumes/Data does not show any snapshots to remove)
  • running disk utility first aid after booting in recovery mode on the Macintosh HD - Data partition. This produces an error...

    Checking snapshot 1 of 2 (com.apple.apfs.purgatory.115b2)
    error: btn: invalid key order (1) oid 1742762 / oxid 0 / level 2 / flags 0x1
    previous key:  [...]
    current key [...]
    next key [...]
    snapshot invalid
    the volume /dev/rdisk1s1 could not be verified completely```
  • disabling SICP using csrutil disable and rebooting

  • running fsck in single user mode:
    • fsck -f which yields: error: container /dev/rdisk1 is mounted with write acess but trying to umount /dev/rdisk1 tells me that /dev/rdisk1 is not currently mounted.
    • Running fsck -f /dev/rdisk1s1 produces the same message.
    • same with running fsck_apfs -f /dev/rdisk1s1

I'm about at my wits end here. Anyone have suggestions for further things to try?


3 Answers 3


The disk utility error is the main issue you face.

  1. Make sure your important files are backed up.
  2. Boot to internet recovery or an external drive so you can re-run Disk Utility not from the booted container. If you can't clear the errors or flush all the snapshots and get a clean run - it's time to erase and reinstall.

Also - you'll want to remove snapshots from all of your volumes - not just /System. find all your volumes on the synthesized volume and check them with diskutil instead of tmutil

diskutil list
diskutil apfs listsnapshots disk1s1

As for the end result - you'll get the most space back deleting the apfs snapshots against /System/Volumes/Data as you mentioned in your post:

diskutil apfs listsnapshots /System/Volumes/Data
diskutil apfs deleteSnapshot disk1s1 -name com.apple.TimeMachine.2019-12-27-124916.local
  • Diskutil reports no snapshots for disk1 (which I verified is the correct disk). Same with your second suggested command - diskutil reports no snapshots. I'm about ready to nuke everything and reinstall, but I can't back anything up either - time machine complains that it "Time Machine could not create a local snapshot to back up from." I've reformatted the external disk about a dozen times with both GUID and Apple partition maps, and in both APFS and HFS+ Journaled case sensitive.
    – bhoward
    Dec 28, 2019 at 0:37
  • 1
    thanks for the suggestions, but I'm definitely working on the right disk... verified with diskutil
    – bhoward
    Dec 28, 2019 at 0:38
  • I'm now trying to create a backup with CCC5, just so I have some backup before I start trying to get medieval on these Time Machine back-ups.
    – bhoward
    Dec 28, 2019 at 0:42

Created a backup using carbon copy cloner, starting woth an external drive formatted to hfs+. Noticed that the backup had plenty of free space, so i figured Id try restoring from it. Wiped the internal SSD to force CCC to partition it, then restored from taht backup and it seems ro have worked.


I had similar symptoms, and just posted my fix on this thread:

Why does my mac not have free space even after I delete files?

hope it helps you.

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