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Time Machine error

Richdmoore said:
For what it is worth, I had the error again just now, and looking at the log posts above determined it was the milod directory. (I previously excluded the widget listed in previous posts.) I used theses instructions to exclude it, as just doing it via the gui time machine did not work (Hidden file?)

https://www.reddit.com/r/applehelp/comments/1imxi0h/timemachine_fails_to_backup_as_some_files_were
Click to expand...

I remember that I also made that exclusion from the terminal. I went back just now to double check and noticed that the directory was not hidden. I also went to a second Mac and noticed it wasn't hidden there as well. I'm not sure what changed. In any case, usually just typing "cmd-shift-." exposes hidden things when using the selection dialog and the Finder in general. (It's just a toggle to show or hide hidden files or directories.) But, I suspect I used the terminal because that toggle failed to show the directory.
 
Jamacfer said:
Since updating to Sequoia my Time Machine backups have been failing during night. Every time I wake up the display, I get the same error: "Time Machine did not finish backing up because some files were unavailable. Backups will resume when your Mac is unlocked." My Mac actually never sleeps; I only put the display to sleep. The next backup after waking the display always works.
Anyone is having the same problem?
Click to expand...
I think I found the solution to this problem. I went to System Settings -> Privacy & Security -> Full Disk Access and added TimeMachine.app. That seems to have solved it for me.
 
My last error was June 8th. July 21 and still not error. I think thats the longest so far. No change with iMac and how I use it. Watch me get it tomorrow because I just jinx myself! LOL
 
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kagharaht said:
My last error was June 8th. July 21 and still not error. I think thats the longest so far. No change with iMac and how I use it. Watch me get it tomorrow because I just jinx myself! LOL
Click to expand...
Yeah, I went a couple of months with no errors and now they've started cropping up again. I am...less than pleased.
 
jloiac said:
I think I found the solution to this problem. I went to System Settings -> Privacy & Security -> Full Disk Access and added TimeMachine.app. That seems to have solved it for me.
Click to expand...
This appeared to have fixed my issue at first, but it did not. When I find the solution, I will post it here.
 
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Found this solution from user Fancy_Expression9255 on Reddit, which I believe is the correct solution. This user describes how to find offending local snapshots and delete them. However, in my case, instead of just deleting the bad snapshots, I decided to delete them all, as well as the backup folder on the NAS. That way I can start fresh with a brand new backup.


You are all on the right track in using Terminal with this command to identify errors.

log show --info --style compact --predicate '(subsystem == "com.apple.TimeMachine") && (eventMessage like[cd] "Failed * acquire device lock assertion*")' --last 24h

But the problem is NOT the files you find listed there, e.g., "com.apple.findmy.FindMyWidgetPeople," or in my case, "com.apple.Maps/Data/Maps/ReviewedPlaceCache-wal."

The problem is the Time Machine local snapshot. (See here for Apple's description of that feature: https://support.apple.com/en-gb/guide/mac-help/mh35933/mac). And the solution is to delete the offending snapshot. Use this command in the Terminal (be sure to include the `/` in the command, that's a shortcut for the volume):

tmutil listlocalsnapshots /

You will get a list that looks like this:
com.apple.TimeMachine.2025-01-18-111742.local
com.apple.TimeMachine.2025-01-18-140944.local
com.apple.TimeMachine.2025-01-18-171400.local

and you will find a match in your error log. Simply delete the offending snapshots with the following command for the appropriate date stamp (you don't need to include the ".local"), for example:

sudo tmutil deletelocalsnapshots 2025-01-18-111742

You may need to delete several or likely even all of the snapshots. Your Mac will then make new ones.
 
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jloiac said:
Found this solution from user Fancy_Expression9255 on Reddit, which I believe is the correct solution. This user describes how to find offending local snapshots and delete them. However, in my case, instead of just deleting the bad snapshots, I decided to delete them all, as well as the backup folder on the NAS. That way I can start fresh with a brand new backup.


You are all on the right track in using Terminal with this command to identify errors.

log show --info --style compact --predicate '(subsystem == "com.apple.TimeMachine") && (eventMessage like[cd] "Failed * acquire device lock assertion*")' --last 24h

But the problem is NOT the files you find listed there, e.g., "com.apple.findmy.FindMyWidgetPeople," or in my case, "com.apple.Maps/Data/Maps/ReviewedPlaceCache-wal."

The problem is the Time Machine local snapshot. (See here for Apple's description of that feature: https://support.apple.com/en-gb/guide/mac-help/mh35933/mac). And the solution is to delete the offending snapshot. Use this command in the Terminal (be sure to include the `/` in the command, that's a shortcut for the volume):

tmutil listlocalsnapshots /

You will get a list that looks like this:
com.apple.TimeMachine.2025-01-18-111742.local
com.apple.TimeMachine.2025-01-18-140944.local
com.apple.TimeMachine.2025-01-18-171400.local

and you will find a match in your error log. Simply delete the offending snapshots with the following command for the appropriate date stamp (you don't need to include the ".local"), for example:

sudo tmutil deletelocalsnapshots 2025-01-18-111742

You may need to delete several or likely even all of the snapshots. Your Mac will then make new ones.
Click to expand...

In my case, the local snapshots which are problematic are the ones made precisely for the failing backup and created at the start of it. Here's a line in my log:

Code: 
2025-03-22 02:07:45.536093-0700 0x205eb3   Error       0x0                  532    0    backupd: (TimeMachine) [com.apple.TimeMachine:FileProtection] 
Failed to acquire device lock assertion for
 '/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/m3/2025-03-22-020714/Data/Users/xxx/Library/Daemon Containers/B22728C8-0EFB-4085-B242-7BACDABBC1B2/Data/com.apple.milod/milo.db-wal' 
(assertion state: <dropped>), error: Error Domain=NSPOSIXErrorDomain Code=1 "Operation not permitted"

You can see the snapshot was created about 30 seconds before the timestamp of the log entry indicating the problem.

Though, perhaps there is some side effect of just deleting snapshots in general that causes some temporary repair to happen.
 
jloiac said:
Found this solution from user Fancy_Expression9255 on Reddit, which I believe is the correct solution. This user describes how to find offending local snapshots and delete them. However, in my case, instead of just deleting the bad snapshots, I decided to delete them all, as well as the backup folder on the NAS. That way I can start fresh with a brand new backup.


You are all on the right track in using Terminal with this command to identify errors.

log show --info --style compact --predicate '(subsystem == "com.apple.TimeMachine") && (eventMessage like[cd] "Failed * acquire device lock assertion*")' --last 24h

But the problem is NOT the files you find listed there, e.g., "com.apple.findmy.FindMyWidgetPeople," or in my case, "com.apple.Maps/Data/Maps/ReviewedPlaceCache-wal."

The problem is the Time Machine local snapshot. (See here for Apple's description of that feature: https://support.apple.com/en-gb/guide/mac-help/mh35933/mac). And the solution is to delete the offending snapshot. Use this command in the Terminal (be sure to include the `/` in the command, that's a shortcut for the volume):

tmutil listlocalsnapshots /

You will get a list that looks like this:
com.apple.TimeMachine.2025-01-18-111742.local
com.apple.TimeMachine.2025-01-18-140944.local
com.apple.TimeMachine.2025-01-18-171400.local

and you will find a match in your error log. Simply delete the offending snapshots with the following command for the appropriate date stamp (you don't need to include the ".local"), for example:

sudo tmutil deletelocalsnapshots 2025-01-18-111742

You may need to delete several or likely even all of the snapshots. Your Mac will then make new ones.
Click to expand...
This is so frustrating. Deleting local snapshots using these instructions worked for a few days, and then it eventually failed. I wonder if I need to do a combination of deleting snapshots and giving certain processes/apps full access. I will do more experiments over the next couple of days and report what I find.
 
jloiac said:
This is so frustrating. Deleting local snapshots using these instructions worked for a few days, and then it eventually failed. I wonder if I need to do a combination of deleting snapshots and giving certain processes/apps full access. I will do more experiments over the next couple of days and report what I find.
Click to expand...

It's a strange thing that deleting past snapshots would allow later snapshots to not have the problem for some time.

Remember that Time Machine is always just backing up a snapshot (assuming the APFS filesystem is being used on the main disk). That snapshot is made right at the beginning of the backup, allowing you to continue to use your main disk without interfering with it being backed up. The error, for me, is always not being able to access some files on that very snapshot. It's weird that deleting such a snapshot after the fact has some effect on later snapshots.
 
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