macOS Tahoe 26.6.2 refuses a 12.89 GB copy over unpurged snapshots (August 24, 2026)
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TL;DR
macOS Tahoe 26.6.2 refused to copy a 12.89 GB file onto a volume that had room for it, because a Time Machine local snapshot holding that space was never purged, according to The Eclectic Light Company on August 24, 2026. The Finder said 'there isn't sufficient disk space', Disk Utility showed the purgeable space inconsistently, and the Finder and Storage settings did not disclose purgeable space at all. Apple has not acknowledged it, no Feedback number is published, and there is no fix as of August 24, 2026.
- Reproduced in a 100 GB APFS container holding about 94 GB of files plus one snapshot made with tmutil localsnapshot.
- Verbatim: 'The Finder and Storage give figures that are incorrect, by omitting purgeable space.'
- On at least two occasions in testing, macOS did not recognize the snapshot as purgeable and refused to purge it when expected.
- The only workaround on this day is to read Disk Utility instead of the Finder, and to copy onto the volume that holds the snapshot, which sometimes forces the purge.
- macOS Tahoe 26.7 reached release candidate 2, build 25G224, the same day, with nothing said about purgeable space.
The test that reproduces it
The setup is deliberately small so the numbers are checkable. A 100 GB APFS container is filled with about 94 GB of large files. A Time Machine local snapshot is taken with tmutil localsnapshot. The files are then deleted, which should leave the container's space purgeable, since the only thing still referring to those blocks is the snapshot.
Copying a 12.89 GB file onto that volume then fails, with the Finder reporting that 'there isn't sufficient disk space'. The space is there. It is held by a snapshot that macOS is supposed to purge on demand, and it does not get purged. Any Mac using APFS with Time Machine local snapshots can be in that state; no Mac model restriction is reported.
The figures macOS shows you are wrong
Three different places give three different answers. Disk Utility shows the large purgeable space, but inconsistently. The Finder and Storage settings do not disclose purgeable space at all, which is why the author writes that 'The Finder and Storage give figures that are incorrect, by omitting purgeable space.' So the number a person is most likely to read is the number least likely to be right.
On the mechanism, the position on August 24, 2026 is candid: 'Time Machine snapshots are purgeable, although they may not always be purged reliably. The cause of that unreliability is unknown.' Beyond the reporting problem, 'on at least two occasions during testing, macOS apparently failed to recognise the purgeability of the huge snapshot and refused to purge it when expected'. The author notes these problems have only got worse over three years.
What Apple shipped that day instead
Apple was mid-cycle on two release trains the same day. macOS Tahoe 26.7 moved to release candidate 2, build 25G224, and macOS Sequoia 15.8 to release candidate 2, build 24H20, according to The Mac Observer on August 24, 2026. The first release candidates were 25G220 and 24H16. The write-up notes that 'The arrival of a second Release Candidate suggests Apple is continuing final testing', and no specific bug or regression is named as the trigger for a second one.
On the next major release, macOS 27 Golden Gate reached developer beta 7, build 26A5421a, with minimal user-facing change, according to 9to5Mac on August 24, 2026. No known issues are named there either. Nothing in either release names purgeable space, so a person hitting this on 26.6.2 has no fix build to wait for.
| Release | Build | State on August 24, 2026 |
|---|---|---|
| macOS Tahoe 26.6.2 | 25G83 | Shipping, affected |
| macOS Tahoe 26.7 | 25G224 | Release candidate 2 |
| macOS Tahoe 26.7 | 25G220 | Release candidate 1 |
| macOS Sequoia 15.8 | 24H20 | Release candidate 2 |
| macOS Sequoia 15.8 | 24H16 | Release candidate 1 |
| macOS 27 Golden Gate | 26A5421a | Developer beta 7 |
The workaround, and what it costs
Two things helped in testing. Read Disk Utility rather than the Finder or Storage settings, because it is the only one of the three that shows purgeable space at all. And try copying the file directly onto the volume that holds the snapshot, rather than onto another volume, which sometimes forces the purge to happen.
The cost is that neither is dependable and neither is discoverable. Nothing in the Finder's refusal points at a snapshot, nothing tells you to open Disk Utility, and 'sometimes forces the purge' is not a procedure. A person who does not already know that local snapshots hold space has no route from the error message to the cause.
What you can do today
1. When a copy is refused for space on macOS Tahoe 26.6.2, do not trust the Finder's figure. Open Disk Utility and look at the container, which is the only place purgeable space shows up.
2. If Disk Utility shows purgeable space, try the copy again onto the volume that holds the snapshot rather than onto a different volume. That sometimes triggers the purge that should have happened automatically.
3. Do not free space by deleting your own files first. The space in this failure is already free in every sense except the accounting, so deleting real data solves nothing and loses something.
4. Treat Storage settings as unreliable for this purpose from now on. It omits purgeable space, so the number it gives you for a volume carrying snapshots is not the number that decides whether a copy succeeds.
5. Expect no fix in the next update. macOS Tahoe 26.7 was at its second release candidate on this day with nothing about purgeable space in it, and Apple has published no acknowledgement to track.
Frequently asked questions
Should I stop using Time Machine local snapshots?
Nothing published on August 24, 2026 recommends that. The reported failure is in how macOS reports and reclaims the space a snapshot holds, not in the snapshots themselves, and no Apple guidance, Feedback number or fix existed on this day.
How do I know whether this is what I am hitting?
The signature is a Finder refusal that says there is not sufficient disk space on a volume where Disk Utility shows a large purgeable figure. If Disk Utility and the Finder disagree by roughly the size of your snapshots, you are looking at this.