What causes Time Machine to stall during backups?

i updated my MacBook Air to MacOS 15.3 two days ago, and so far the backups have been completing on schedule without issue. My schedule is only once per day though. I have forced a couple of backups since updating. and they completed successfully too.

Before the update, I was changing Lock Screen settings to keep the MacBook from locking or sleeping during backups, and I kept it powered during the backup. Those tricks worked most of the time. This morning, I noticed that a backup completed overnight with no special Lock Screen settings, and the laptop was closed and only on battery power. Under these conditions I would have fully expected any overnight backup to fail, so when it didn’t, I was stunned. Maybe there’s something to 15.3? I’m cautiously optimistic but still skeptical. Fingers crossed, but time will tell I guess.

Third party backup issues were resolved in 15.3, maybe fixes are in there for TM too. It should be noted on my wife's iMac she had the TM backup issue, and none at all since upgrading to 15.3 (with a new external drive).

good day to you, luigi. you know, it should be easy to respond to comments. it's not. sad. i recently updated to 15.3 on both of my mac minis and my macbook. all are running ™ backups to completion. so far.

bruiselee13 wrote:

good day to you, luigi. you know, it should be easy to respond to comments. it's not. sad. i recently updated to 15.3 on both of my mac minis and my macbook. all are running ™ backups to completion. so far.

As I've pointed out before, if you sort the thread by "oldest" and include the comment you're responding to - as I have above - it makes makes it much easier to follow the thread of comments. They're not the greatest boards for threading, but you and the others complaining about how difficult it is to follow things really are making it more difficult for yourselves.

Zurarczurx wrote:

As I've pointed out before, if you sort the thread by "oldest" and include the comment you're responding to - as I have above - it makes makes it much easier to follow the thread of comments. They're not the greatest boards for threading, but you and the others complaining about how difficult it is to follow things really are making it more difficult for yourselves.

Hi Zurarczurx! Because my comments were default sorted by "Rank," I missed your original post reminding us to look for that itsy, bitsy, teeny, weeny button to change the sorting options. Having said that, why my comments were sorted by "Rank" baffles me because I set my preferences to sort by "Oldest" years ago. Anyway, thanks for your reminder post. I reset my preferences to "Oldest" and now there is sanity to this discussion.

Update, sent the following through to Apple Support:

..............as you know I've been rebuilding the Mac slowly and logging what

changes I've made. All has been well with the TM backup problem not

coming back, until this morning when it reappeared. When the Mac was

unlocked this morning I got the usual 'Backup Not Completed

Time Machine couldn't back up to "TM Extreme SSD as files were in use......' message.

The only changes I'd made since all was well was to add the 'Home'

and 'Notes' widgets to the desktop. The triage this further I?'m now

removing the 'Home' widget and seeing if that fixes the problem. If it

is still there then I'll look to remove the 'Notes' widget.

Other changes that were made included Brave browser extensions, so I'll look at those on a secondary basis.

Fingers crossed......

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.

15.3 Didn't fix the issue no, but as I said in the other post removing the Notes and Home widgets from the desktop seem to have made a difference. Since removing them I've not had a single TM backup problem.

Early days yet and I'm still monitoring but it's a good indicator.

It makes me wonder how many of you having the problem are using desktop widgets and if you are which ones?

I'm now using Apple Weather, Clock and third party Countdowns widgets with no problems.

Hi dbreewood! Too bad 10.3 didn’t work for you. I thought I’d help you out with a little feedback about your widgets hypothesis. If others do the same, maybe you can track down an offending culprit. My wife’s M4 Mac mini had the TM problem (until I switched to Carbon Copy Cloner 7). The widgets she was using when TM was ravaging her were Weather, Calendar, Battery, and Find My. Hope that helps. This is a good mystery. Better than most.

Hi dbre! Before posting, I have developed the habit of copy and pasting any comment I write here and place it in a folder in the Notes app in case I need to retrieve it. Ironic that I backup comments in a discussion about TM backups! Am I correct in understanding that 15.3 did NOT solve the problem but then you tried removing certain widgets and that DID solve the issue, hopefully permanently? As a retired teaching scientist, I can't help but be curious what would happen if you added back the suspicious widgets to confirm your hypothesis. (One of them could have been corrupted. A one off sort of situation.) But, if TM problems return, that sure makes those widgets look guiltIER. But BEFORE removing them, I'd update to 15.3.1 and see if that solved the problem. If 15.3.1 solved the problem WITH the suspicious widgets still installed that would seem to be a better situation for you as you could then avail yourself of those widgets with impunity. I apologize in advance for suggesting you do even more work on top all the investigative effort you have already done. I'm just a slave to my curiosity.

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.

Hi dbre! I was excited when I read your first comment which aggressively pointed to a guilty Home widget. But, then I read your follow-up and even though a reboot seems to have fixed it, I am less excited. Why? This completely reminds me of the problem I had for a LONG time with “unlocking my Mac” using my Apple Watch. I kept trying to find the culprit and every once in a while something would surface that appeared to work for a while only to have the failure to unlock return. It turns out the problem had NOTHING to do with ANY of the things I tried that occasionally looked promising. BTW, if you’re curious what the REAL problem was, it turned out to be that I had gone deep into settings when I first bought my 2018 Mac Mini and turned ON “Log out after 1 hour of inactivity.” I didn’t know that if you’re logged out of your machine, the Apple Watch will not “Unlock My Mac.” This dangerous move was not mentioned in Apple’s “Unlock my Mac” literature back then. I have noticed they DO include the instruction to not turn on “log out after…” in their current literature. Anyway, not to be a Debbie Downer. I do home the Home Widget IS the culprit and this solves your problem forever. If I was using TM (and not Carbon Copy Cloner 7), I would install the Home widget so we could get more data. Maybe someone here who is using TM and has no problems could install the Home widget and see what happens? You know…in the spirit of science. 😊

The tale continues. TM backups are still continuing without any issues when the Mac is locked.

One thing I'll be looking to re-test is the Home Widget, I will be adding it back in later. Why you ask......

Well I had removed it as you know on the Mac, but have it in place on the iPhone. When I came to use it last night I noted the 'tile' for the desk keyboard light was saying 'no response', tapping on it did nothing.

New the lightstrip I have under my desk (and above the keyboard drawer) is a Nanoleaf product. I went into the Nanoleaf app on the iPhone and was advised I needed to update the firmware. I was on version 3.6.196 and the latest version was 4.13, so quite a way behind. Anyway that has ben updated and the tile on the iPhone widget now works.

So....... that makes me think was this firmware 'problem' also affecting the widget on the Mac? No ideas, but I want to see if the backups remain stable (as I've a few bits of 'awkward' software to install today).

If things are looking good I'll add the widget again and report back as to how it goes.

Hi dbre! I don't have any Nonoleaf products so I have nothing to offer there. But I did want to write to commend you on your Sherlock Holmes skill set in hopefully solving this problem in your use case. Well done. 👏👏👏 P.S. I wish many of these IoT products had a better notification system for letting you know when updates are available.

Thanks Luigi. The point in my mentioning the Nanoleaf firmware issue was not to criticise them but to highlight the possible issue of third party Homekit devices interfering with systems. My systems have been perfectly working for nearly 3 days now without an issue. However I'm not considering it fixed yet, more testing is needed before I'll be happy.

The last Apple issue I had to resolve took over 14 months before I resolved it, Apple gave up, but that one I determined was caused by a rogue app.

I've been testing software as a side-line for over 35 years now so I'm patient enough to go through the steps needed to resolve issues. As a retired Production Engineer and IT Engineer / Manager I've got an unusual skill set which suits this sort of investigation, plus I never ever give up. :)

Anyway onwards and upwards....