Sequoia Time Machine Synology NAS keeps disconnecting

When will Apple crushes this bug finally? In version 20? Djeezzz.

It’s not an Apple bug. It is a Synology bug.

Prior to their SMB 3 implementation, they use Netatalk which is a hack of Apple Filing Protocol (AFP). Apple has never licensed AFP. When Apple switched to SMB networking, they set a specification for Time Machine over SMB. It is up to Synology to support that specification.

I am running the final release of macOS 15 and fixed the issue by going to Apple > System Settings > Privacy & Security > Full Disk Access > toggle ON smbd. It seems macOS 15 disables the 'smbd' by default. The 'smbd' option provides filesharing and printing services using the SMB protocol which is what Synology is using to broadcast its file and folder shares.

I'm experiencing a similar issue. Time Machine backups occasionally fail, and file transfers to my NAS over SMB frequently cause my Macbook to disconnect from the NAS.

MacBook: Apple M3 Pro MacOS 15.0 (24A335)

NAS: DS918+ DSM 7.2.2-72806

Thank you for posting your experience. so you essentially re-did the macOS<>synology time machine integration and it's still not working the same as it was prior to the update from sonoma to sequoia? new folder, proper time machine folder settings, create the new time machine backup, etc... you did all that and it's still not working? ughhhhh

For me, that's always been the workaround that i've found solves these problems after a new macOS update. When macOS updates, can't think of a year that I wasn't forced to completely reintegrate time machine with my synology. it's always awful every year, but at least it still works in the end... not this time tho?

'Fraid so.

I've chatted with Apple twice now.

The first time they asked me to try and start the iMac Pro in Safe Mode (failed with same error); to create a new account (failed); and reinstalling Sequoia (initially seemed to work, but then it failed overnight with the same error and has failed every time since).

I've chatted with them again and I'm waiting for a call back. First line support is saying they've not heard of this error before, so I have pointed them to this thread.

My MBA is updating completely reliably throughout.

I'll keep people informed.

I am afraid the problem is on Apple's side.

I have a Synology DS218+ at home, and I have this issue with my MacBook Air recently updated to Sequoia.

I back up the same MacBook Air at work on a Western Digital My Cloud NAS, and I have precisely the same problem.

I have the impression it is triggered when I leave the computer unattended (inactivity? Sleep?), even if in the Battery panel I have ON the switch "Prevent automatic sleeping on power adapter when the display is off".

I tried only once an overnight backup on an external SSD, and next morning I found the red dot with the "i" in the Time Machine control panel and the message "backup could not complete because some files are not available...etc."

Hope they fix it in 15.0.1/15.1.

Yes, that worked for me too, for a while and then it suddenly stopped working again. I saw a post here (that I now can't find) that suggested re-starting in safe mode and then re-starting normally. I did that and, with the firewall off, my backups are working again. Not sure quite what that did, but certainly did the trick for me.

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.

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).

Disabling the firewall on your Mac can indeed resolve issues with Time Machine backups, particularly when using a Synology NAS. Here’s how to do it and some additional context based on user experiences:Steps to Disable the Firewall on macOS

1. Open System Settings:Click on the Apple menu in the top-left corner of your screen.Select System Settings.
2. Navigate to Network Settings:In the sidebar, click on Network.Scroll down and click on Firewall.
3. Disable the Firewall:Click on the toggle to turn off the firewall.You may need to enter your admin password to make changes.
4. Test Time Machine Backup:After disabling the firewall, attempt to initiate a Time Machine backup again.Check if the backup completes successfully without interruptions.

Additional Considerations

• Firewall Rules: If you prefer to keep the firewall enabled for security reasons, consider setting specific rules to allow Time Machine traffic. This can often be done by allowing connections for specific services or applications related to Time Machine.
• Network Configuration: Ensure that your Synology NAS is properly configured for Time Machine. This includes enabling SMB (as AFP is deprecated) and ensuring that your NAS is accessible from your Mac without restrictions.
• User Permissions: Verify that the user account you are using has appropriate permissions to access the Time Machine share on your NAS.

User Experiences

Many users have reported that disabling the firewall resolved their backup issues, as it allowed Time Machine to communicate freely with the NAS. However, it's advisable to re-enable the firewall after testing and configure it correctly to maintain network security.If you continue facing issues even after disabling the firewall, consider checking other network settings or consulting Synology's support documentation for further troubleshooting steps.

Updating the SMB Service package to the latest beta (v4.15.13-2319) on my Synology NASes appears to have resolved the issue for me — at least for the time being.

Interesting. And I should add I am running a Macbook Pro M1 so the macOS 15 for Intel seems suspicious.

Wow nice… will be neat if I don’t have to delete my backup history every year. Thanks for posting that!

Update: No. 15.0.1 did not solve the problem. The problem re-occurred today.