Sequoia Time Machine Synology NAS keeps disconnecting

I am getting this issue with my QNAP TimeMachine Backup and also with RDP sessions disconnecting with a data encryption error:

https://learn.microsoft.com/en-gb/answers/questions/2100561/windows-app-0x407-data-encryption-error-after-upda

Pointing to the Mac Firewall, I turned it off and the errors disappeared both for the backups and the RDP sessions.

There are always going to be bugs in any major release of software like Sequoia, nobody is perfect, not even Apple.

Adrian.

These problems are widespread and it may not be related to NAS at all. Many, many users are experiencing inability to maintain persistent connections in 15.0.1. Some are reporting turning off the Apple firewall as working. Do NOT turn off the Apple firewall if you don't have something like Little Snitch installed and properly configured. If you have no choice, please complain to Apple support.

M1 Macbook Pro backing up to Time Machine on Synology NAS DS 920. Upgrading to Mac OS 15.1 addressed the problem of Time Machine failing to complete, as others have noted.

[Edited by Moderator]

Confirmed that 15.1 fixed this for me, for both the Synology NAS and external USB drive Time Machine backup.

Locally macOS 13 and macOS 14 are working with Synology configured for Time Machine Server. DSM 7.2.2 with update. Testing included full restores.

Here is the Synology NAS setup (also linked in a reply above):

• https://kb.synology.com/en-global/DSM/tutorial/How_to_back_up_files_from_Mac_to_Synology_NAS_with_Time_Machine

If it is still not working, I’d suggest updating to current DSM if not already, and then asking this question again over in the Synology forums: https://community.synology.com/enu/

No macOS 15 in production yet (locally), so no Synology TM support testing (here).

After additional days retrying backups, only way to get them succeed is disabling the Firewall

Still on Sonoma but recently had this issue - 3 different laptops all kept giving same failure to Synology NAS Time Machine backup. Eventually just had to delete that TM setup, start as new and works on all now.

Similar issue here on an iMac Pro running Sequoia and a Synology DS218j with the latest Desktop Manager 7.2.2-72806. The Synology is not reporting any problems.

My Time Machine backups initially worked after updating the Mac, but have now repeatedly failed and I haven't been able to get them running again. I've even created a new backup folder on the Synology to see if it is an incompatibility with previous backups.

I can get the backup started after a very long 'Preparing to back up...', it finds the changes and then begins copying files to the Synology, however it stops abruptly before being completed and never gets to the cleaning up stage.

I don't get any sort of pop-up alert warning, nor does the Mac itself say the Time Machine drive has disconnected, but the little red error symbol gives the same Time Machine error you're seeing about the disk disconnecting whilst in use. The drive remains mounted on the Desktop and in Finder.

Trying to Verify backups through Time Machine also results in the same error.

I've tried rebooting the Mac and the Synology but the error persists.

I wasn't getting this issue before the update to Sequoia, so something behind the scenes has definitely changed. Unfortunately, Time Machine's rather terse messages about what it is doing aren't helping me see where exactly things went wrong.

I fired up TheTimeMachineMechanic after a failed backup and its results are:

Analysis from 2024-09-21 12:22:24 +0100 to 2024-09-21 14:22:24 +0100 for 2 hours:

Backing up 1 volumes to Backups of Hekla (/dev/disk3s1,TMBackupOptions(rawValue: 0)): /Volumes/Backups of Hekla 2 on which there were 3.93 TB, 3.93 TB available.

Current free space on backup volumes: 0))

No auto backups started in the period, no backup has been completed successfully in the period,

Created 0 new backups, and deleted 0 old backups,

Created 1 new snapshots, and deleted 6 old snapshots,

Of 0 volume backups:

0 were full first backups,

0 were deep scans,

1 used FSEvents,

0 used snapshot diffs,

0 used consistency scans,

0 used cached events.

✅ No error messages found.

⚠️ Running check on scheduling system (CTS and DAS).

DAS appears to be rescoring normally over the last 90 minutes.

Running CTS check next.

CTS has not been told to run a backup in the last 90 minutes. Scheduling may have stopped.

Consider restarting your Mac.

Hopefully this is a teething trouble from a new OS release, but I might need to attach an SSD as a temporary backup drive until the issue is resolved by either Apple or Synology - though I think the only drive I have spare is one of those potentially flaky SanDisk portable drives :(

spoona wrote:

I have just upgraded my 2018 Mac Mini to MacOS 15 Sequoia.

Since 2019 it has always backed up to a folder called TMFolder on a Synology DS413j.

( My partner's Mini also backs up to the same NAS, but hers is still on Sonoma. Her backups still run successfully. )

Every time Time Machine on my Mini tries to backup to the NAS now, it reports:

https://discussions.apple.com/content/attachment/210afe65-c27a-4054-a7f0-293a6a494cf0

The backup will fail anywhere between one and five minutes after starting.

Unfortunately, 15.0.1 does not fix the issue, at least for me. MacBookAirM2 and Synology DS218+ (but also a WD iCloud at work) and iMac-M1 on an Airport TimeCapsule. If the Mac is not active when the backup is scheduled, the backup fails with the error "Some files were not available...". If TM backup starts when the Mac is active (i.e., if in the meantime, I am working on it), then there is no error, and the backup succeeds.

Prevent automatic sleeping when the display is off in the energy saver panel is active/turned on.

I keep thinking the problem is on the Mac side since everything worked fine with MacOS14, and the problem appeared with MacOS15. I have the same problem with 2 Macs (Air-M2 and iMac-M1) and on 2 different NASs (Synology and WD).

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.

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.

Don't know if this is what did it since I've tried several different things, but I went to Network>Firewall>Options and added the Time Machine app to the list of allowed connections. I've had one successful backup since, but it's such an easy thing to try, I thought I'd post it.