Monterey Time Machine not working

Immediately after upgrading from Big Sur to Monterey on my M1 MacBook Air, most of my Time Machine backups stopped working. I have one backup going to a network drive, the other four go to locally connected USB drives that are rotated between locations. Only a single one of the USB connected drives continued to work all the others show the same symptoms:

The backup starts and then appears to work fine (giving me number of bytes backed up and a time estimate of what's left), and it gets almost done, according to the progress bar, and then it just stops. No errors are displayed, it just stops. When I open the time machine control panel it just shows the last backup as the one immediately before the Monterey upgrade.

I took one of the offending drives and erased it using the disk utility, then removed and re-added it as a Time Machine volume. Time machine picked up the drive and began backing up to it and appeared to back up nearly the entire machine (~600GB worth). When it was almost done (just a few minutes left, according to the progress bar), it just stopped. Relaunching the backup on that drive will cause it to back up a gigabyte or so and then it just stops when almost done.

Any assistance would be appreciated as only one backup is happening. Thanks

MacBook Air (2020 or later)

Posted on Oct 28, 2021 12:52 PM

Top-ranking reply

tundraespresso

Level 1

8 points

Posted on Jan 5, 2022 9:02 PM

The Apple support person got back to me today. Engineering requested that I run the command:

tmutil addexclusion ~/Library/Containers/com.apple.findmy*

and try backing up again. After running that command, the next backup succeeded. If I removed the exclusion (tmutil removeexclusion), the next backup failed; if I re-added it, the next backup succeeded. No other changes were needed.

Presumably the engineers were basing the exclusion on these errors in my Time Machine log, which other folks have also seen:

2022-01-05 20:52:41.604577-0700 localhost backupd[540]: (TimeMachine) [com.apple.TimeMachine:FileProtection] Failed to acquire device lock assertion for /Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/[computername]/2022-01-05-205219/Macintosh HD - Data/Users/[username]/Library/Containers/com.apple.findmy.FindMyWidgetItems/Data/Documents error: Error Domain=NSPOSIXErrorDomain Code=22 "Invalid argument"

All of the errors like this in my log referenced items that fit the pattern “~/Library/Containers/com.apple.findmy*”. For those who want a workaround to get TM to mostly work, searching the Time Machine log entries for those “Failed to acquire device lock assertion” errors (or any other errors that appear to happen when backups fail), and tailoring your TM exclusions to what you find, might help. (Again, this echoes what other folks have said.) For those who aren't helped by this workaround, consider logging your case with Apple.

Meanwhile, at least there’s evidence that Apple engineering is working on it, even if they’re not currently very far ahead of us.

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Monterey Time Machine not working

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