What causes TimeMachine backups to fail on NAS devices?

In my case after update to 15.0.1 the "preparing to back up" step takes 30-50minutes...

Before update it was up to 3-5minutes max!

The backup step itself is quite fast as usual.

I have SMB QNAP Network share.

Disabling the Firewall , new TM setup, delete a few latest backup did not help as well...

Metoo here after 15.0.1 update. Read that turning off is a temp solution. However. I have a company laptop where turning off firewall is greyed out. So no option for me.

I truly hope Apple will fix this issue. This is a serious problem!

It appears it is not just TimeMachine backups to SMB shares. VPN's, RDP connections, DNS lookup requests, 3rd party network security products etc.

Suggest everyone uses the feedback tool on their Mac's and report the issue, that is what that tool is for.

Lets us hope an update fixes this quickly, I can imagine quite a few systems will be affected.

Adrian.

This isn't just NAS's. I have two Mac Mini's and an MacBook Air. The Air is a M2 running 15.0.1 on of the Mini's is a M2 running 15.0. The third Mini is the target and it is older. It is an i7 running 10.15.7. All it does is act as the target and has worked for years until this update. The 15.0 machine works fine the 15.0.1 machine, no dice. I have gone as far as completely reformatting the target drive and reconnecting the Air to it. The connection is initially made and the sparse bundle is created but then the backup goes into the abyss and I get a failure that says the remote disk disconnected.

I am yet to look into the firewall fix that people have been talking about but this as someone said is a complete dumpster fire. Apple has really dropped the ball with 15.0.1. That 15.0 machine isn't getting the update anytime soon.

To add my tuppence worth, it’s more than just backups.

if you search you will find it looks like the Mac’s ability (or lack of) to communicate properly with devices on a local network.

I’ve had issues with RDP connections to machines on my local LAN, VPN issues into my local LAN and have seen reports of app developers struggling to get their programs to pop the “allow access to local lan?” message and I’ve also seen reports of DNS queries failing if the DNS server is on the local LAN.

Agreed it is really terrible and shoddy testing on the part of Apple.

These are not budget devices we invest in and I expect a bug as big as this one to be caught so early in the testing process so as not to appear in the public release.

I have fed back to Apple with my diagnostic logs.

Mine stuck at "connecting to backup disk..." and the log just said "Bonjour resolution not possible for 'afp://backupworker@x.x.x.x" indefinitely. Apparently I'm able to mount the AFP volume in Finder or `mount_afp` and I can tell Bonjour broadcasting works just fine, but the Time Machine just can't.

I have just updated three machines to 15.1.1 (avoided 15.1).

One is a mac mini 2018 intel, which has two LaCie drives attached for network time machine backup, the others are both MBA Mx laptops.

One of the MBAs was on 15.0.0 while the others were on 14.7.0. In that situation, I had various and many failures with the networked disks disappearing during a backup of the 15.0.0 machine. Also repeated failures of screen sharing to the mac mini.

With all machines on 15.1.1, those problems have stopped. I have run several backups from both laptops to the mini and screen sharing between all three works fine.

This has been a very unsatisfactory series of events, and I'm sure that it hasn't entirely gone away, especially as some NAS users are still having problems.

In conversation with an Apple person, I asked why they didn't have field testers (you or me) who could run through the non-standard setups that are likely to occur in abundance outside Cupertino. The response was that if I encounterd a failure, I could mail the logs, but there was no plan to introduce field testing of that kind. In the dim and distant, I worked on IBM MVS/370 -- IBM's standard policy seemed to be to ship buggy software, then let the users fix it and send the patches back to base for distribution round the world. It wasn't ideal, but it worked.

Apple, perhaps you could give it a thought. The Beta programme obviously didn't pick up this mess.

I may have a clue about what the problem is.

I have an old Synology NAS DS213j. Under 15.01 I needed to turn off the firewall in order to make a backup. Somehow when I upgraded to 15.1 things worked. I though the bug went away.

But it scared me enough that I decided I should get a NAS that's not a decade old and can run modern software. So I bought a Synology DS224+ and installed it. I tried to backup using timemachine to it. It fails in the way everyone's been reporting. Turning off the firewall doesn't help. BTW 15.1 vs 15.1.1 doesn't make any difference.

There are two large differences between the working old machine and the new one. The new one is much faster. And the new one is running the 7 Synology OS where the old one is running the 6. I've done my best to use the same settings but in the new OS.

My guess is the bug has something to do with a timing error, and that turning off the firewall perturbs the timing enough that it doesn't appear for some people.

I'll try to call Apple tomorrow when their first string help desk is available. But I don't expect to get any more success than everyone else has had.

I have called Apple support twice since I first reported it on 03-Nov-24. They are in complete denial. This past weekend I spoke to a Senior Advisor instead of the first level support (Advisor) and he acknowledged that this is an Apple issue but he was completely un-interested in offering any solution or information. So, I wasted 2-3 hours trying to get more information and re-escalating this Apple MacOS bug. I find it baffling that they are not concerned about some form of bad interaction between the Firewall (or security) and another OS important function like TM.

I write code and have worked with coders. The worst bugs to find are the ones that can't be replicated.

I suspect that the folks at Apple can't reliably cause the problem to occur. The emotional response probably is denial. They can't fix it, they look at the code and see nothing wrong, they can't replicate it so it must be user error. So they may have had reports of problems for a while, but I don't think the people in charge of fixing it are really convinced it's happening.

The only way to get past that is if enough people complain that they realize they need to do something. The sr. advisor I spoke to said they were blaming Synology for the problem. But if they get enough complaints they work with other companies even if they believe the problem is theirs. Argh.

I have already reported to them twice that it is happening also with Time Machine with both NAS and USB connected hard drives. I do not know what do they need to convince themselves that this is on THEIR end and not the users. The update to 15.0.1 broke it for me when TM was working fine with both methods.

Turning off the Apple OS firewall is not an elegant workaround that they should be proud about.

Even turning off the firewall doesn't work all the time. On my old NAS server on Sequoia 15.0.1 I needed to turn off the firewall to make a backup. But when I upgraded to 15.1 it worked -- on the old NAS server. However the episode convinced me to get a modern NAS server and I can't make a backup to that now, with or without the firewall. I'll keep the old NAS server until Apple fixes things. I suppose it's possible that I did screw up the installation of the new NAS.

I spoke too soon. My backups are still failing. I am running an MBA M2 on 15.1.1, and the target machine is a Mac Mini 2020 Intel I7 on 15.1.1 with two attached LaCie drives. This setup has been running perfectly well for four years. Only on upgrade to > 15.0.0. did it fail.

The error I get is mid-backup - see screenshot. It happens when the MBA is on battery with the lid closed. To be clear, this has previously worked with no problem. To test, I have set Put Hard Disks to Sleep to <NEVER> and Wake for Network Access to <ALWAYS> Will report if that makes any difference.

@MarkWegman - when I migrated my wife's Intel MBA on 14.7.1, to her new MBA M3 on 15.0.1, the first T-M backup corrupted the existing sparsebundle. Fortunately, I had backed up the sparsebundles before migrating.

[Edited by Moderator]

Here is a link for you to voice your concerns to Apple

Feedback - Time Machine - Apple

I have never used a NAS but the experts that are far more knowledgeable than myself would probably not recommend it. I read a article about TimeMachine yesterday and a question similar to yours was asked in the comments.