Time Machine did not finish backing up because some files were unavailable. Backups will resume when your Mac is unlocked.

..... And I can confirm the issue was fixed after the restore, but that was on macOS Sonoma, as soon as I uplifted to Sequoia the issue returned, as I expected.

I've just spoken to Apple Support again and she is going to investigate and cal me back tomorrow.

If it is any use to anyone my case is 10*******93.

If you have reported the case and have a case number please feed it back, as she did indicate she was not aware of any other reports. If you have not reported it please do so and feel free to reference my case number.

The more of us that report it the quicker it will get resolved.

[Edited by Moderator]

It's just lazy customer support to ask users to wipe their TM drive and/or Mac hard drives (and restore or reinstall macOS). There is obviously a NEW bug in macOS 15 that is causing this when TM kicks off and the screen is locked. Obviously. Wiping everything only papers over the problem and DOES NOTHING to find the real issue.

I say "lazy" without any guilt. I do customer support for a software company and I always want to find the real cause rather than paper over it. Look how many people are impacted by this!!! The real number is 1 or 2 orders of magnitude more! (because people don't spend the time finding a place to post their problem)

I'm very sorry to say but the 'fix' didn't work for me at all. I went through all the steps in full, and this morning after being out for a walk, with the Mac locked I returned to find the errors were back!

Exactly the same situation, 'some files unavailable' so the backup could not complete.

Now I'm working on the Mac (that is it is unlocked) the backups are now taking place and completing without any errors.

Apple need to fix this issue.

Guys yesterday I realised that Spotlight was not indexing things properly on my Mac. I then followed this support article, and added / removed the hard drive on the Mac as well as excepting a few drives.

This morning I accessed the Mac and I had no TM backup errors at all. W00t!

So is it worth you guys reinitialising Spotlight and seeing if it fixes your errors? Worth a try!

I'm curious about the solution. I've the same issue which has occurred from Sequoia 15.0.1 onwards (now running 15.1). This is on a Mac Mini 2 Pro.

I have three TM backups:

• external drive (via USB-A hub)
• external drive USB-C
• To a share on my Synology NAS

It looks like the solution involves getting the Mac into save mode and then reconnecting TM. I wasn't sure that was possible for the network share to the NAS, but if it is…

Then the big question is… when re-adding the drive into TM, what do you do with the existent TM backup, re-use it, or start again with a fresh backup?

I'm assuming here that for the NAS, the existing bundle in the share needs to be deleted from the NAS side of things?

Any further thoughts or info would be appreciated.

Have you tried reindenting Spotlight as I advised up thread? It solved the issue instantly for myself and my wife?

Same errors after getting around the Firewall issues brought in with MacOS 15.0.1 on a MacBook M1 Pro. This is a disaster of an update by Apple. The issues with Time Machine because of the update are not acceptable. Still, Apple support has not provided any solutions.

It doesn't fix the issue.

I've been on to Apple Support most of the afternoon. Their suggestion was to wipe the Mac and restore from a TM backup.

Foolish me thought it'd also restore all the apps settings, nope...... So I'm slowly launching apps and reconfiguring them all! I'm not happy!

This probably means that the workaround of sorts (deleting the backup sparse bundle is hardly a workaround) that works for Sequoia 15.0.1 does not work for 15.1. So, between 15.0.1 and 15.1 they made the bug worse. This must be all related to the security changes they make. Too much security?

Apple needs to fix this serious bug fast now that you have found the hard way that it is worse with Sequoia 15.1.

Yep I saw that they had made the edit alas. I just checked and it seems we can't contact each other via PM on here either. You can try contacting me on Mastodon search for tekguru on the Vivaldi instance. Unless of course they edit this out too :)

I'll bite the bullet and stick with Sequoia and if needful backup manually until it is resolved. I'd class it as a critical issue they need to resolve.

I found this on reddit:

log show --info --style compact --predicate '(subsystem == "com.apple.TimeMachine") && (eventMessage like[cd] "Failed * acquire device lock assertion*")' --last 8h

to find the file. For me (and others on reddit since macOS 15.0):

Timestamp               Ty Process[PID:TID]
2024-11-15 17:02:28.528 E  backupd[322:533fa9] [com.apple.TimeMachine:FileProtection] Failed to acquire device lock assertion for '/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/max/2024-11-15-170051/Data/Users/xxxxx/Library/Containers/com.apple.findmy.FindMyWidgetItems/Data/SystemData/com.apple.chrono/snapshots/com.apple.findmy.FindMyWidgetItems/systemSmall---4259486853547037044----164.00w--164.00h--20.00r--0f--0.00t-0.00l-0.00b0.00t.chrono-timeline' (assertion state: <dropped>), error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

Really seems like a new bug, Apple. Stop telling people to wipe their machines!!! Ask them for this info!!!

In any case, at best it might be addressed in 15.2 or 15.2.x with any luck since as you found out, the support team is not aware at large of the issue as you found out. According to the second tech support person I chatted with yesterday said that the “engineers were aware of it”. However, with 15.1 the issue is worse than with 15.0.1.

I do not see it listed in known issue or an official explanation by Apple in the support pages. There is another thread specific to NAS backups failing: What causes TimeMachine backups to fail o… - Apple Community .

Not good.

Well, I tried it all again this time with the firewall off. And as you can see it didn't make a ****** bit of a difference.

I can see that I'll have to raise it as a bug with Apple......

In either case, you need to erase the previous backups. Must start fresh.