What causes Time Machine to stall during backups?

It doesn't fix the issue.

I've been on to Apple Support most of the afternoon. Their suggestion was to wipe the Mac and restore from a TM backup.

Foolish me thought it'd also restore all the apps settings, nope...... So I'm slowly launching apps and reconfiguring them all! I'm not happy!

This probably means that the workaround of sorts (deleting the backup sparse bundle is hardly a workaround) that works for Sequoia 15.0.1 does not work for 15.1. So, between 15.0.1 and 15.1 they made the bug worse. This must be all related to the security changes they make. Too much security?

Apple needs to fix this serious bug fast now that you have found the hard way that it is worse with Sequoia 15.1.

Yep I saw that they had made the edit alas. I just checked and it seems we can't contact each other via PM on here either. You can try contacting me on Mastodon search for tekguru on the Vivaldi instance. Unless of course they edit this out too :)

I'll bite the bullet and stick with Sequoia and if needful backup manually until it is resolved. I'd class it as a critical issue they need to resolve.

I'm very sad to say that the problem has returned for me (again). I've forced a Spotlight re-index (again), and so far it seems to have fixed the issue. I've fed back on my ticket with Apple that the issue is back.

When you reformat your external drives, do you let Time Machine format the drives for you? I remember formatting this way just before my TM backups started working. Make sure your format is APFS Case-Sensitive, because I was formatting manually using non case sensitive APFS, until TM formatted my drive for me. To do this, remove your drive in TM settings, (it will not delete your contents at this point) then restart Mac and re-select your drive for backups. Very quickly, your drive will come back online formatted and ready to go, but of course, your previous data will be erased. My TM is still working this morning. Hope this helps.

I format the drives manually as 'APFS Volume • APFS (Case-sensitive, Encrypted)'.

Interesting in removing the drive and re-adding after a reboot. I've done this before and T M has never reformatted the drive, just used what was already there. Next time it fails I'll try adding that schema into my 'fix' notes :)

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.

To add the exclusion on my system I had to do the following in a Terminal session with Full Disk Access enabled:

sudo tmutil addexclusion -p ~/Library/Containers/com.apple.findmy.FindMyWidgetItems/Data/SystemData/com.apple.chrono/snapshots

It happened to me. Time Machine failed to back up. Then it deleted my entire two year history of backups.

Time Machine cannot be trusted. This isn't the first time it deleted years of backups.

I've removed it, cleaned up its remnants (like the hidden snap shots consuming about 100gb), and reformatted my backup storage.

Now I'm using Carbon Copy Cloner. It's great. It's what Time Machine promised to be, and a lot more.

I've had the same issue ever since migrating to a new M4 Mac mini, but never had the issue on my older M1 mini running the same OS version. Backs up fine when using the Mac, but not when it is locked. I've tried all the relevant fixes here (Firewall, that Find My folder exclusion, Spotlight reindex) to no avail. I back up to a NAS, and maybe related to this issue found myself needing to erase and reset my backups, but did that all within Time Machine, not by manually deleting the disk image.

Can't necessarily say this is more than an annoyance, as realistically the backups do work the only times files only on my Mac that I care about are likely to change (while using the Mac) and I back up just daily, but it is definitely annoying. Maybe we should wait for the next OS update and see if that changes anything, given the issues all backup tools are having in 15.2?

MODERATORS! HELP! Something is wrong with this discussion regarding how comments are presented. They are NOT in chronological order but rather in some random way and it is incredibly difficult to find responses to posts. ALSO, comments are disappearing. I posted a comment yesterday, Jan. 31, asking if MacOS 15.3 had fixed the problem. That comment is now gone. dbrewood posted on Feb. 1 a series of steps he had performed and the result was that his TM backups were working for 5 straight days. That comment is also gone. I have searched every page of this discussion for the above two comments and can't find them. I wonder how many other comments have disappeared. BTW, if I missed the above comments and they are actually somewhere in this discussion, I apologize. But if I am correct, would you kindly check out this issue and see if it is rectifiable? In advance, than you for your assistance. Mr. Luigi

i can't find mr luigi's post to respond to so i'm posting here. this is really in agreement with

"MODERATORS! HELP! Something is wrong with this discussion regarding how comments are presented. They are NOT in chronological order but rather in some random way and it is incredibly difficult to find responses to posts. ALSO, comments are disappearing. I posted a comment yesterday, Jan. 31, asking if MacOS 15.3 had fixed the problem. That comment is now gone. dbrewood posted on Feb. 1 a series of steps he had performed and the result was that his TM backups were working for 5 straight days. That comment is also gone. I have searched every page of this discussion for the above two comments and can't find them. I wonder how many other comments have disappeared. BTW, if I missed the above comments and they are actually somewhere in this discussion, I apologize. But if I am correct, would you kindly check out this issue and see if it is rectifiable? In advance, than you for your assistance. Mr. Luigi"

i agree. i can't find anything. a scatter post algorithm is not helpful. plus, mr luigi is correct that posts disappear.

I've been trying to work out commonalities between my old Mac build, the new build and the apps my wife uses. Alas logic does not allow any apps which may be common across all machines.

I still think it's a macOS issue.

In any case, at best it might be addressed in 15.2 or 15.2.x with any luck since as you found out, the support team is not aware at large of the issue as you found out. According to the second tech support person I chatted with yesterday said that the “engineers were aware of it”. However, with 15.1 the issue is worse than with 15.0.1.

I do not see it listed in known issue or an official explanation by Apple in the support pages. There is another thread specific to NAS backups failing: What causes TimeMachine backups to fail o… - Apple Community .

Not good.

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.