Sequoia Time Machine Synology NAS keeps disconnecting

In my case I had updated to 15.0.1 and then experienced the problem. Turning the macOS firewall OFF was the only way I've found to complete a backup to my Synology NAS. Previously I was able to back up with the firewall on while on Sequoia 15.0.

This is a known issue with the firewall in macOS 15.0.0 and 15.0.1, which causes disconnects… I guess we’ll just need to wait for a bug fix.

Hi everyone,

As promised here is an update - and it *might* be fixed. My machine has been backing up reliably now for about 24 hours without issue.

I've had a couple of chats with Apple's support team here in Europe - and first of all - lovely people, really friendly and patient. It doesn't look like we've found a root cause for the failure, but on my setup it looks like the preferences files in the Time Machine sparsebundle might have been corrupted after the update.

My 'fix' was time consuming. Be warned.

After turning off Time Machine temporarily, I opened the sparsebundle in Synology DiskStation (it appears as just another folder), deleted the three .plist files in the sparsebundle, then closed the sparsebundle.

Restarting Time Machine and triggering a Time Machine backup caused the machine to generate a new sparsebundle - this took HOURS, but since completing the first backup the machine has been backing up regularly including when asleep.

I haven't tried it, but I assume deleting the sparsebundle entirely would have the same effect - but that felt pretty drastic. After the backup was completed and verified, I could delete the old sparsebundle.

Not sure why this worked and creating a new folder on the Synology a few days ago did not, nor do I know if this is a permanent fix - but I am making backups again.

HTH.

spoona wrote:

Well, in my case, it's neither an Apple bug nor a Synology one.

I use some anti-malware/anti-intrusion apps from Objective-See Foundation. I disabled both BlockBlock and LuLu and the issue went away. I'll be sure to pass on this info to Objective-See !

Add-on security apps have a very long history of introducing issues and errors and noise, yes.

Had the same situation - since 15.0.1 backups with Time Machine to Synology failed. For me it is the macOS firewall - disabling it and the backup just works fine, enabling it and the backup failed. Not sure yet why tough...

Same here, Synology NAS worked fine for years, 15.01, and it died. I turned off the Firewall on my Macbook pro M1, and it worked fine. Does anyone know if we can put a SMB firewall exception rule to allow it to work with Firewall on?

The issue of the firewall may be a sub-issue. I don't have the firewall on, and TM backups fail both on my synology NAS and on my WD MyCloud NAS. In my case, it appears to be linked to the Mac sleeping/locking, even if system settings=>battery=>options I have "preventing automatic sleeping on power adapter when the display is off" is checked. And on 2 different macs (laptop and desktop). No issue with Sonoma, failing backups with 15 and 15.0.1.

I have had issues with SMB mounts and Synology and macOS for years now.

My mounts would just disappear. Sometimes there is the "all these mounts have broken" popup. When that happens, there is nothing wrong with the NAS, nothing wrong with the network. The mounts just go bad.

I have a python script which I use to manage my mounts, with a `--keep` flag to actively monitor for when they go away and re-mount. This has worked well (so long as I remember to restart it whenever I reboot). TimerMachine usually worked.

After migrating to Sequoia, my script started failing. All it does when monitoring mounts is:

1. ensure the mount path exists, if not, create it.
2. perform an `lstat()` call on the path.
3. perform and `lstat()` call on the path+"/.."
4. If they are on the same device, the mount has been removed, so re-mount.

After Sequoia, this has been failing. One failure mode is that the test to see if the mount path exists indicates the path does not exist, so I attempt to create it, and get an error that it exists. Prior to last week, never a problem, so the code just caught the error and exited. Now, I have to catch and retry, and that makes things better.

There are other occasions where the check for 'path' exists succeeds, but the `lstat` tests fail. Waiting for that to hit again so I can drill down on it.

Since Sequoia, I have seen situations where things get locked up and cannot be fixed. I think a reboot has been required here, not just a "Force Quit". Not sure, as I have not really been focusing on this issue, so it was several days ago last time I tickled it.

If anyone wants my script, I can try to package it with some documentation. It keeps the credentials in the keychain, and has an embedded table of mounts to manage. I need to clean it up so the table is not embedded and so that it does run at start and has some better docs.

My wife does not use the script and she often restarting Finder to recover NAS mounts when they get lost on her machine. This has always been a side effect of SMB mounts to Synology in my experience.

Apple is not to blame if the Synology Server does maintain a proper TM handshake. Synology doesn't use a licensed version of Apple software. They are forced to use a public domain version of AppleShare that may simply not yet be compatible with a new major release of macOS such as Sequoia. That puts Synology in a bind too.

There are things that one must handle in the Synology Diskstation configuration settings too such as keeping current with DSM 7.2.2 and ensuring that in Control Panel > File Services you are using SMB 3. Synology has this Mar 4, 2024 article on Time Machine though that may not be enough if there is an incompatibility lurking.

I have a new DS119J downstairs with DSM 7.2.2 and 16 TB configured and I still don't attempt TM backups to it. Otherwise, file sharing works just fine with released Sequoia v15.0.

@tmelander,

This helped me. Thank you very much.

More thoughtlessness from Apple. Firstly, it shouldn't be missing from the default installation. Secondly, you can't even add this smbd process easily from System Settings. It's so locked down that you can't search for it in the location window that appears. You have to use a separate Finder window, open a folder here: /usr/sbin and then manually drag the 'smbd' app into the System Settings location window. "It just breaks" is the new slogan.

I also have connection issues with M1 iMac: the Citrix connection were dropping every 20-40 mins others report dropping ssh connections. The "solution" for me was to disable firewall and rely on my router to do the "firewalling".

Full disk access for smb was already enable under privacy settings.

I am having EXACTLY the same problem with both my MacBookAir M2 and with my iMacM1, both on Sonoma, and either when they back up on the Synology NAS (DS218+, 7.2.2) or on an old Airport Time Capsule. This started after the Sonoma upgrade and seems to happen when the computers are inactive/sleeping. I have the impression the backup might start, but then it is aborted because the Mac goes to sleep and cuts off the connection. Files "unavailable" and backup tha will resume "when your Mac is unlocked" let me think about an issue on the mac/sonoma side.

Synology SMB Services beta didn't help me (with DS218+) - still "Backup couldn't be completed...", no matter whether via wifi or LAN. Time Machine on SSD connected via USB-C does however work.