macOS 11.6.1 vs Time Machine

I posted in macOS 11.6.1 thread, but my problem continues and I’m hoping this will get more visibility.

I installed macOS 11.6.1 (and Safari 15.1) on Oct 28. On that date, Time Machine stopped completing its updates, both to a Time Capsule and a dedicated external drive. Several days later, on the Time Capsule, I deleted my backup (by telling Time Machine to stop using the Time Capsule and deleting the sparsebundle file on the Time Capsule disk) and then started a new backup. Time Machine continued to fail to complete backups, until Nov 20, when it completed its one and only backup since the macOS 11.6.1 install.

If I click on the red exclamation point next to the backup target in the Time Machine pane in System Preferences, I get the following message.

Time Machine couldn’t complete the backup to [disk name]
Time Machine did not finish backing up because some files were unavailable. Backups will resume when your Mac is unlocked.

Normally I am in user account, but I did restart and login as an administrator to see if that would enable Time Machine to finish. It didn’t.

I don’t understand what files would be unavailable and I don’t understand why Time Machine thinks the Mac is locked. Any help? Anyone else have this problem with macOS 11.6.1?

Hello. I have exactly the same problem on my Macbook Air M1. It started when I upgraded to Monterey 12.0.1. I’ve not been able to complete an update since 12/11. I have no idea how to fix it.

I doubt that I will be able to do anything meaningful with the information, but do you recall what macOS version you updated to 12.0.1? Time Machine worked for me while I used 11.6, but then stopped working when I installed 11.6.1. As noted above, I installed Safari 15.1 at the same time. Not noted above, I also installed an unversioned Device Support Update.

Thanks for the report. I had hoped that a later update would fix it, but it sounds like that would not be the case, at least not yet.

I can’t remember precisely what version of Big Sur I was on before Monterey. It will have been whatever was shipped with the MacBook at the time. I’m relying on CCC for backups at the moment as I’m not confident that TM is doing anything reliable.
I have had to stop using Safari 15.1 as well as it freezes and loads very slowly on many web pages. I’ve made Firefox the default browser for the time being.

In this situation, consider beginning a new TM backup on a newly formatted drive. This would help determine if your TM backup problem is OS version related and, possibly, restore confidence in TM backups.

I realize you were not replying to me. However…

I did begin a new Time Machine backup, but not to a newly formatted drive, because (unless I’m mistaken) that would have destroyed the Time Machine backups of two other users, who continue to back up to the Time Capsule without difficulty. Also, I have an external drive (not Time Capsule) used for Time Machine backups, and it also began failing to complete backups immediately after the installation of macOS 11.6.1.

Just for giggles, try using Disk Utility’s First Aid feature on your Mac’s boot disk to see if there might be some corruption that it can fix.

Just tried that and all is reported as fine. Thanks. Worth a go.

I’ve run a TM backup on a new conventional external hard disc formatted as APFS (Case-sensitive). This has backed up several times this morning without a problem. The external SSD, the one where I’m having the problems since Monteray is, I’ve noticed, formatted as a Journaled HFS Plus volume. Not sure whether that has anything to do with it. It’s happy with the partition that CCC uses. If I reformat the external SSD I’ll lose over 6 months back ups. It’s the Time Machine couldn’t complete the backup to [disk name]
Time Machine did not finish backing up because some files were unavailable. Backups will resume when your Mac is unlocked’ that we can’t resolve.

I should have thought of that. Thanks, and I’m glad it worked for @david.n.watts.

After running First Aid in my user account, Time Machine again failed. I restarted and ran First Aid in an admin account. In both the user account and the admin account, it apparently found no errors. Time Machine is currently trying to back up in my user account, and I’m not hopeful.

I did see these messages.

warning: container has been mounted by APFS version 1933.41.2, which is newer than 1677.141.2
warning: disabling overallocation repairs by default; use -o to override

Do those mean anything to anyone?

An update. After successfully running a new version of TM onto a separate HD yesterday I switched back to the original external SSD and tried again - no change to formatting, just the same file. Today it ran successfully without the message about locked files. Admittedly it took hours to finish the ‘cleaning up’ routine but, whatever was causing the error message and preventing a full backup, seems to have cleared by dint of switching to another disc then back again.

I don’t know if it’s related, but I had one successful backup to Time Capsule (on Nov 20) since updating to 11.6.1 (on Oct 27). I didn’t record when I deleted the earlier Time Machine sparsebundle file, but it was many Time Machine backup attempts before the successful backup.

Based on your report, I might try deleting the Time Machine backup on the external disk, and maybe using Disk Utility to wipe it clean. In case I want to do that, would someone confirm that I want to use GUID Partition Map and Mac OS Extended (Journaled) file system for a Time Machine external disk?

My understanding is that GUID and HFS+ Journaled will allow Time Machine to reformat a new volume to APFS as required.

Maybe I should have said that the external disk is a spinning disk. Certainly Disk Utility says it is currently formatted GUID Partition Map and Mac OS Extended (Journaled) and Time Machine had been working with it before I installed 11.6.1. Might that be the problem? (I wouldn’t think going from 11.6 to 11.6.1 would make that difference, but I wouldn’t know.)

In any event, I could certainly format it as APFS (and lose all the Time Machine history, but hope that it starts working), but I thought that APFS offered no advantage on spinning disks.

And today, Time Machine just started working. I have no idea why. Certainly I made no conscious change.

FWIW, Cleaning up took about three hours. I assume all those failed attempts each left some detritus that needed to be addressed.

Encouraged by the successful Time Machine backup to Time Capsule, I attached an external drive with another Time Machine backup and told Time Machine to back up now. (I had disconnected it after six weeks of failed backups.) That backup also succeeded; Cleaning up took 14.5 hours. Again, I assume each failed backup left some detritus. (I had deleted the Time Capsule backup after weeks of failures in a vain hope that a fresh start would be successful, so it had many fewer failed backup attempts.)

It will be interesting to see if future backup attempts succeed, both immediately and (later) following a computer restart. Right now, it’s been five hours since Cleaning up finished, and Time Machine has not attempted (or at least not succeeded with) an automatic backup to either volume.

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