What causes Time Machine to stall during backups?

I resolved the issue after working with an Apple support person. I have an MBP M1 Pro with MacOS 15.1.1. and I had failures with TM both on NAS and hard wired backups. My workaround, as per the boards, was to to turn off the MacOS Firewall to let the backups work to completion.

However, I also have a cyber security software which includes a firewall of its own. There is a conflict between its firewall and the MacOS one starting with Sequoia 15.x. After I turned off the security software firewall and left the Mac OS one active, all TM backups work without error. The 3rd party cyber security software firewalls need to be updated for Sequoia.

I resolved the issue after working with an Apple support person. I have an MBP M1 Pro with MacOS 15.1.1. and I had failures with TM both on NAS and hard wired backups. My workaround, as per the boards, was to to turn off the MacOS Firewall to let the backups work to completion. The issue with the lockup screen seems related to the security issue I was seeing.

However, I also have a cyber security software which includes a firewall of its own. There is a conflict between its firewall and the MacOS one starting with Sequoia 15.x. After I turned off the security software firewall and left the Mac OS one active, all TM backups work without error. The 3rd party cyber security software firewalls need to be updated for Sequoia.

I resolved the issue after working with an Apple support person. I have an MBP M1 Pro with MacOS 15.1.1. and I had failures with TM both on NAS and hard wired backups. My workaround, as per the boards, was to to turn off the MacOS Firewall to let the backups work to completion.

However, I also have a cyber security software which includes a firewall of its own. There is a conflict between its firewall and the MacOS one starting with Sequoia 15.x. After I turned off the security software firewall and left the Mac OS one active, all TM backups work without error. The 3rd party cyber security software firewalls need to be updated for Sequoia.

A further update sent to Apple:

......further updates. A lot of testing today doing an in depth analysis of changes made again yesterday, covering app configurations, browser extensions, etc. Backups still failed with the Home widget removed.

I've now removed the Notes widget and so far all backups have been fine.

This follows on from previous reports where desktop widgets were looking somewhat problematical.

I'll continue to monitor and update you when things change.

So far rock solid.

Okay, sorry for the delay in replying, but I did want to give things a decent run through concerning the widget situation.

First the Notes widget was added and there were no issues with TM backups.

This morning I added back in the Home widget and the next TM backup ran while the Mac was locked. It failed. I ran it manually with the Mac unlocked, and it completed as expected. I started a backup manually and quickly locked the Mac - I unlocked the Mac 5 minutes later and the backup had failed.

I removed the Home widget from the desktop. I then started a backup manually and quickly locked the Mac - I unlocked the Mac 5 minutes later and the backup had succeeded. I tested this twice more and the backups all succeeded.

I will of course continue to monitor, but it does look like (for me at least) that the TM backup problem is caused by the Home widget being in use on the desktop.

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!!!

I am seeing this error after updating to Sequoia, too, but I'm not interested in completely erasing and reformatting my backup drive yet because I'm hoping for a real fix. I'm currently running 15.1.1 on a MacBook Air.

I've had some success with backing up either while I'm actively working on my Mac and thus keeping the hard-drive active or changing System Settings>Time Machine>Options>Back up on battery power>Off and System Settings>Lock Screen>Turn display off on power adapter when inactive>"For 3 hours" or "Never" when I want to be backing up. This seems to prevent the computer from locking, which is what the error message seems to be suggesting is a problem. I'm lucky because I work from home, so if my computer sits unlocked for awhile it's not an issue. But I have to remember to reset the Lock Screen setting if I'm taking my computer someplace where the lack of security would be an issue. This is an inconvenient work-around, but at least I'm getting backups done, for the most part, until Apple actually fixes the problem.

i followed all the instructions without success. however, i had my drive plugged into a usb port expander (d-link). i plugged the disk directly into the usb port on the mac mini and had no problem. i also have an m2 laptop with a usb passport drive. that drive has always been plugged directly into the computer and i have not had any problems.

Following the changes made yesterday:

• ........
• Forced a Spotlight reindex
• Went into TM settings and excluded all external drives from the Backup
• Went into Spotlight Privacy and excluded all external drives as well as network shares from being searched.

TM backups have been working perfectly every hour with no errors at all.

Go into the TM settings use the options button to choose disks to ignore. Add the main hard drive on the Mac, wait 30 seconds and then remove it. That should force the indexing to reinitialise and solve the problem. Fingers crossed.

Interesting. Arq Backup started having a problem with a file similar to that as well. Excluding ~/Library/Containers/com.apple.findmy.FindMyWidgetItems/Data/SystemData/com.apple.chrono/snapshots allowed it complete.

Regarding Time Machine HD issue. I have now 3 week the Apple Mac mini M4 and trouble with Time Machine. I have tested some ssd HD. Not really any chance, that the Time Machine is working longer without trouble.

My solution is to use a Standard HD like this e.g. Toshiba Canvio Basics 1 TB. This is a mechanical HD. And I have used a USB C to USB A adapter. Now the TimeMachine is working two weeks without any problems. Ok, the HD is not the fastest. Cheers, Thomas

Since the dating of this discussion is all over the place on my Mac, I will start off by saying I am posting this on Jan. 1st. I previously posted that I had a license for Carbon Copy Cloner 5. I stopped using CCC 5 a while ago as I didn't really need its extensive functionality. However, after all the hassles I have had with TM and my M4 Mac Mini I decided to revisit the CCC website. Happily found out yesterday that I qualified for a discount on the latest version of Carbon Copy Cloner 7 because I had paid for CCC 5. So I bought CCC 7 for a very reasonable price of about $30. I installed it on my Mac mini and set it to back up every hour on the hour. That was 24 backups ago and CCC 7 has worked flawlessly. IMO, the money spent is well worth not having the hassles of TM. Clearly, Bombich software, who makes Carbon Copy Cloner is putting more effort into their product than Apple is with TM. As an experiment, I kept my 2nd backup hardrive connected to TM but set it to back up every "hour + 1 minute on the hour + 1 minute." So 5:01, 6:01, etc. Because CCC 7 initiated a backup at 5:00, 6:00, etc. the TM backups scheduled for 1 minute later ARE ALL PROCEEDING nicely. No more failed backups. At least for one day. If things stay as they presently are, I will continue to dedicate one of my backup harddrives to CCC 7 and one to TM. If TM starts to get naughty again, I am going to abandon TM completely and use CCC 7 on both my backup harddrives. I hope my experience is of help to some of you. I remember when I got my 2018 Mac Mini, the "Unlock my Mac via Apple Watch" feature performed very poorly despite many folks having the same problem. To this day it continues to perform poorly. So I don't hold out any hope that Apple will fix TM with our Macs and refuse to be jerked around anymore by the problem. I consider the $30 spend on CCC a great investment in performance and sanity.

I fed this detail back to Apple Support today:

Hi ......., thanks for coming back to me.......

The problem did indeed return even after completely erasing and rebuilding the Mac and using a reformatted external drive for TM backups.

While I've been rebuilding the Mac in stages I've been logging every single change with respect to apps being loaded and any changes made within MacOS itself.

At the point the issue returned I had added a widget to the desktop (from a third party app) and after completely uninstalling that app the problem has gone away. I'm continuing to monitor as in the old MacOS install I had thought the problem was resolved only for it to return a few days (or weeks) later.

I'll keep you updated as to how things proceed (within the 4 weeks ticket close period).

Trusting you are duly informed.

I'm hoping the 'widget' issue was what caused the issue for me, and it does make me wonder how many of you fellow suffers are using widgets, especially third party ones?