Time Machine couldn't complete backup.

[rbpeirce]

We seem to be far adrift of the original problem. I suppose I have not been sufficiently clear.

I have two TM backup drives and I've scheduled one backup a day. I always get the first backup (on alternate drives, as expected) but sometimes TM tries to do a second on the same day. I have no idea why. It took me a while to realize but this second attempt seems to be what produces the error that the backup stopped because some files could not be accessed.

I never had a problem until I upgraded to Sequoia, which may or may not be the problem. The actual problem is not exactly life threatening. I just ignore it and I get a backup the next day. However, I was curious about what was going on, hence the original post.

 

[ferrarr]

What time is TM scheduled to back up to each drive? In Settings, it will show the last time it was backed up, and since you have it scheduled for once a day, they both should be completed around the same time, just with different dates. And, does the error (Notification?) you get, have a time stamp, for comparison?

 

[rbpeirce]

What time is TM scheduled to back up to each drive? In Settings, it will show the last time it was backed up, and since you have it scheduled for once a day, they both should be completed around the same time, just with different dates. And, does the error (Notification?) you get, have a time stamp, for comparison?

To the best of my knowledge you cannot specify a time. Looking at my TM settings, it backed up to one drive yesterday at 6:28AM and to the other today at 7:07AM. Generally I think it tries to do this around 7AM each day.

The error message does not have a time stamp that I am aware of but I always get the error when it tries to do a second backup on the same day. I have no idea why it even tries to do a second backup on the same day because it alternates days when it is working right.

 

[Jimmysb]

What time is TM scheduled to back up to each drive? In Settings, it will show the last time it was backed up, and since you have it scheduled for once a day, they both should be completed around the same time, just with different dates. And, does the error (Notification?) you get, have a time stamp, for comparison?

I have my TM on daily, and the back ups are not 24 hours apart, more 23 -25 hours.

 

[MacInWin]

To the best of my knowledge you cannot specify a time. Looking at my TM settings, it backed up to one drive yesterday at 6:28AM and to the other today at 7:07AM. Generally I think it tries to do this around 7AM each day.

The error message does not have a time stamp that I am aware of but I always get the error when it tries to do a second backup on the same day. I have no idea why it even tries to do a second backup on the same day because it alternates days when it is working right.

I don't think one sets the time for TM backups directly. Rather, when one turns ON TM and it makes the first backup, it then repeats at the set interval FROM THAT TIME. So, if your initial backup was a 6:30 AM, it should repeat every 24 hours at roughly that same time. The actual time might vary a bit, based on what is going on with the machine at the time. As for why it might try two in one day, I have no idea what might trigger that, unless the one that fails is FIRST, because it will then try again and again until the failure condition goes away.

 

[eicca]

SOLVED!

So I ran this command to see why Time Machine failed:

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

And it returned this:

2024-11-16 21:48:05.711 E backupd[697:195fb68] [com.apple.TimeMachine:FileProtection] Failed to acquire device lock assertion for '/Volumes/com.apple.TimeMachine.localsnapshots/Backups.backupdb/Treadstone/2024-11-16-214705/Macintosh HD - Data/Users/[USER]/Library/Containers/com.apple.findmy.FindMyWidgetItems/Data/SystemData/com.apple.chrono/snapshots/com.apple.findmy.FindMyWidgetItems/systemSmall--8516498320056292854----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"

For some idiotic reason it can't back up ~/Library/Containers/com.apple.FindMyWidgetItems or FindMyWidgetPeople when the computer is locked.

Lots of other people having the same issue in other forums, same folders causing Time Machine to crap the bed if the computer is locked.

So I set my exclusions as so:


Now my Time Machine has been running backups successfully even when the computer stays locked for days at a time.

Keep in mind, when you go to add the folders to exclusions, they do not have the com.apple part in the folder name. That only appears once added to the exclusion list.

This is particularly infuriating cuz I don't even use the Find My widgets.

I really miss macOS Mojave. It truly Just Worked. I've had to spend half of my time setting up my M2 Pro Mac Mini just finding workarounds for the truckloads of bugs they've introduced since 2019.

 

[rbpeirce]

I'm still convinced this is a Sequoia issue since it always worked before. I keep hoping for an update to correct it. In the meantime, I find I can manually start the backup when I'm logged in and it works fine. However, that shouldn't be necessary

 

[eicca]

I'm still convinced this is a Sequoia issue since it always worked before. I keep hoping for an update to correct it. In the meantime, I find I can manually start the backup when I'm logged in and it works fine. However, that shouldn't be necessary

It probably is. Apple’s software QC just gets worse with every release.

 

[rbpeirce]

I haven't had this problem since upgrading to 15.2. Maybe they fixed it or it hasn't had a chance to rear its head.

 

[Slydude]

I haven't had this problem since upgrading to 15.2. Maybe they fixed it or it hasn't had a chance to rear its head.

I started a new TM backup last night and it was still running when I went to bed. I woke up this morning and the backup had failed to complete with this same error. I ran a backup manually this and it seems to have finished the backup started last night. Unfortunately the next scheduled hourly backup failed so the problem is still there.

I'm on the most recent Sequoia update although my Mac is back to telling me that an update is available even after I run the update.

 

[rbpeirce]

I started a new TM backup last night and it was still running when I went to bed. I woke up this morning and the backup had failed to complete with this same error. I ran a backup manually this and it seems to have finished the backup started last night. Unfortunately the next scheduled hourly backup failed so the problem is still there.

I'm on the most recent Sequoia update although my Mac is back to telling me that an update is available even after I run the update.

Still going strong. Are you running 15.2? I just checked and was told that was the latest for my M1 MBP.

I'm only doing daily backups but these show one at 1:25PM on 12/23 and one at 2:47PM yesterday. I have no idea how the time is determined. I've not had a failure since installing 15.2.

 

[MacInWin]

Time is determined, generally, by the initial time you started the first backup and the interval you have chosen. It's not precise, as it can be delayed by several things, including the unavailability of the backup drive, some system events, etc. If, for any reason, a backup is seriously delayed, the clock starts over at the time the backup completed. So, for example, if your original backup was at 1:20 PM with daily backups, the second backup will start about one day after the first one finishes. If that first finish is seriously delayed for any reason, TM will try to get back to the original timing, but again, not precisely.

What is happening is that at the expiration of the interval set for backups, TM will examine the drive to see if anything has changed that needs to be backed up. If so, then it triggers the next backup and at the end, the timer is reset. In the default 1 hour interval, the movement is very small, just a few minutes, but with daily backups, the movement can be large if the files needing backup are large and the process slow.

For Sly, at the next failure you can use Howard Oakley's Mints utility to search the log for TM errors. I seem to recall that his T2M2 isn't functioning properly on Sonoma yet. You can check at his website.

 

[Slydude]

Still going strong. Are you running 15.2? I just checked and was told that was the latest for my M1 MBP.

Yes. I just double checked and I am on 15.2 on myM1 Mini. I installed it the day of release or the next day IIRC,

I double checked the software update notice I'm getting and it's actually a notice about the 15.3 Developer Beta.

 

[ferrarr]

Unfortunately the next scheduled hourly backup failed so the problem is still there.

Did you restart your Mac?

 

[Slydude]

Did you restart your Mac?

I hadn't thought of that but I'll give it a try.