Since update to MacOS 15.0.1 Time Machine backups do not work

I wish I found this thread a two weeks ago, but I have some good news. After struggling with this for days, I contacted Apple. After days of back-and-forth calls with them, my third Advisor confirmed that in macOS 15.0.1 they introduced a bug in the Firewall feature, that they are working on a fix (hopefully a soon-to-be released 15.0.2), and there is no setting that we can make to create a firewall pinhole (which I asked for).

In the meantime the recommended work-around is to set Time Machine backups to be manual (not hourly or daily), to turn off the Firewall when ready to do a TM backup, manually kick it off, and (when it is done) to turn the Firewall back on. Effectively, we have to "lower shields to use the Transporter" (Trek fans will recognize the analogy). It sucks, but at least it gets the job (sort of) done.

I would recommend, before you run your next TM backup, you "lower shields" (Firewall) and option-click on the TM Menu Bar icon to run a Verify process to be sure that this problem hasn't corrupted your TM backup. After this happened (on October 3), my TM back up was corrupted and I had to start over (twice or three times during the debugging process).

[Edited by Moderator]

Seems to be a MacOs Sequoia Firewall Issue! please try to deactivate temporally the Firewall, and force a Timemachine Backup (don't forget to reactivate firewall when your backup finishes), so have to wait unti Apple fixes the Issue with the Firewall

Sad to report that Sequoia 15.1 does not change the problem for me. I reliably get the failures with firewall on, and never with firewall off. My backups are from a MacBook Pro M3 Max (Sequoia 15.1) via TM to a networked Apple Mini (Sequoia 15.1) with two hard drives connected via USB to the Mini.

Just to add I've had this problem too. I've been back and forth with Synology as I'd just (coincidentally) upgraded my NAS at about the same time as the MacOS update, and as there are quite a lot of errors in the Mac logs relating to Time Machine not being able to access the SMB share I believed this was a Synology thing.

However, I have disabled the firewall on my Mac and finally (after about 10 days back and forth) the Mac is backing up to the NAS. Not sure the full implications of the 'shields down' since I have a firewall running on my Ubiquiti gateway.

Here's hoping for an Apple solution soon, in the meantime the disabled firewall workaround is holding up for me.

Hi,

since I was seeing the same issue with macOS 15.0.1, I am not seeing it anymore. If I remember correctly, under version 15.0.1 disabling the firewall was helping as a workaround, and starting with version 15.1 TM backups and other remote services did work even with the firewall enabled.

It is maybe a long catch, but have you disabled AFP on your NAS? I have my Synology (620slim) configured to use SMB only, and I did not encounter any issues anymore using TM or any other services on the NAS.

BTW.: Im using a MacBook Pro 16 with Apple Silicon.

I received a note from tschloesser with the suggestion to turn off AFP. Now, before I did that I had updated DSM to 7.2.2 as well. I think turning off AFP did the trick but I need to go back and check this to be sure. I'm just using SMB and, right now, everything is working like it did before.

Thanks to tschloesser for the suggestion.

Good news : upgrading to macOS 15.2 fixed the issue for me.

I could re-enable the firewall and the Time Machine backup did not fail as it did before.

Sequoia 15.1.1 also did not fix the problem for me. Note that my configuration is all Apple (MacBook Pro to networked Mini to its attached HDDs). TM backups work with MacBook's firewall down, fail with it up. Apple definitely owns this one.

Ok kiddies. The good news with 15.2 is that (apart from the Apple Intelligence that I've decided to leave setting up until later) is that Time Machine is now FIXED once more!!! Goodness knows what they did in the 15.0/15.1 releases but that has now been backed out and it's all working again.

I do hope that the culprits are doing suitable penance, having to serve Tim C his afternoon tea from the plantations above Foxconn, served on a tray made of recycled prototype iPhone cases that were only ever touched by the hand of Steve Jobs. The tea would be served to the strains of Jean-Michel Jarre's "Fishing Junks at Sunset" so everyone can reach their afternoon Zen point.

Subsequent to my previous posting on this thread and elsewhere, I can confirm that my TM backups to my Synology NAS now happen consistently nightly as expected, under Sequoia 15.2.

To get to that point I did have to deleted my previous (pre-Sequoia) TM backups and start afresh, and under 15.1.1 I did use AutoMounter app to maintain the "link" so that the network connection did not drop. I now no longer need to use that.

Excluding onedrive and Dropbox from back up worked.

This is really good news, but I since I am seeing more such issues related to broken connections, I hope Apple will not set a focus on TM but on the general underlaying problem.

for example I was using a remote session to an lab environment with Chrome and the connection was broken in random intervals! After a while I remember weed the TM issue and turned the local firewall off. After this change I did not face any connection related issues anymore.

I'm currently using Sequoia 15.3 iMac to a Synology DS7.1.1u7. Time Machine backup is working as expected, every night on schedule.

As you may see from my previous post above, under 15.1.1 (no firewall) I had to delete my previous TM backup on the NAS and start from scratch - a pain, and use an app to maintain the connection to the NAS to make it work.

Under 15.2 it seems that "connectivity/timing" issue was addressed, and I have dispensed with the AutoMounter app. No change under 15.3 - TM backup working as expected.

Confirm. After disabling the firewall, the backup will run smoothly.