Sequoia Time Machine Synology NAS keeps disconnecting

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.

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.

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.

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...

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.

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?

I had this problem too...

I found in "System Settings" -> "privacy and security" an entry for "Full Disk Access". Time Machine was not in it.

I added and enabled "Full Disk Access"

Time Machine is working!

I don't remember seeing this setting in sonoma.

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 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.

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.

After disabling the firewall and waiting for a successful backup to complete, I enabled the firewall again.

I was sure the next backup would fail, but it didn't and Time Machine completed several daily backups since.

Bravo. I disabled MacOS Network Firewall and the backup immediately started running. Per some other posts with similar results, I will let it run a few days and then

1) re-enable firewall with current settings. if that fails again, I'll

2) re-enable firewall with updated settings to accommodate Time Machine settings.

Thanks much for the help

The issue is the Private WiFi Address for a WiFi Connection.

My WiFi subnet was 192.168.4.0/24, but I was getting an IP Address of 192.168.5.63 when connected. I was not able to browse or ping to any device on the 192.168.4.x subnet. I could not print either.

Turning off the "Private WiFi Address" and then disconnecting/reconnecting to my WiFi network resulting in getting a 192.168.4.x address and I was able to backup to my NAS and browse to it.