TimeMachine Big Sur to Synology NAS

I'm having the same problem with a WD MyCloud drive so it isn't limited to Synology.

Up to macOS 10.14.x (Mojave) TM backups were saved as sparsebundle. With macOS 10.15.x (Catalina) TM backups were saved as a backupbundle. There were many complaints that under macOS 10.15.x (Catalina), previous TM backups saved as sparsebundle were not accessible.

Now with macOS 11.0.1 (Big Sur) TM backups are saved (again) as sparsebundle. Perhaps it follows that a sparsebundle created with Big Sur is not compatible with a backup created in Catalina as a backupbundle.

I think I may have figured out what is going on here, although I can't understand the why. After sending Synology the debug.dat in response to the Support Ticket I started I began examining the Connections log in DSM. I noted that each time one of my Big Sur systems tried to access the NAS from TimeMachine there were 2 user connection entries nearly simultaneously - the user I had designated in Time Machine, and another user I had previously designated - both with privileges for that backup shared folder. I went back into DSM and eliminated all those user privileges to that shared folder except the general admin user. I then went back into the Big Sur Time Machine and deselected and reselected the appropriate NAS, entered the general admin user credentials and then initiated a Time Machine backup.

So, in short, have only a single dedicated user in DSM with privileges to your TimeMachine folder, unselect the drive in Time Machine and then reselect it using that dedicated user's credentials. That is what seemed to do the trick for me.

I would just like to know why Big Sur was spitting out 2 sets of user credentials for each attempted logon to the NAS.

A couple of other items I took out of the mix were: (a) removed Sophos AV (which has only a semi-effective implementation to begin with) and (b) turned off Spotlight indexing altogether (just adding the Synology Time Machine share didn't do any good since as soon as you disconnect the drive it disappears from the exception list).

I have left all the settings I had for NAS under Catalina, just uninstalled Sophos and found that my first TimeMachine backup is running fine under Big Sur.

Will reinstall Sophos once the first backup is complete. On the Sophos website they are saying they may release a Big Sur compatible update next week. This may correct the issue. I currently have different users for separate TM backups.

After many hours of work, I was able to SOLVE it on my machine.

I was having this problem (TM error 112) on one upgraded Big Sur machine, while others are backing up fine to Time Machine folders on Synology NAS.

After doing many things (several times), I was able to solve this.

1) Followed these Synology Instructions to make sure it's not Key corruption issue: https://www.synology.com/en-global/knowledgebase/DSM/tutorial/Backup/What_should_I_do_to_fix_the_problem_when_connecting_to_Synology_NAS_using_Time_Machine

2) Deleted Time Machine folder on NAS.

3) Deleted old user and setup a new Time Machine User on NAS.

4) Turned off Sophos Home Anti-Virus

All of that did not allow me to go further than creating a sparsbundle on NAS, with TM Preparing Backup, but then fail in ability to write files to the the NAS sparsbundle.

What finally solved it was:

5) Uninstalling Sophos by downloading Sophos removal tool. https://support.home.sophos.com/hc/en-us/articles/115005499786-Uninstalling-Sophos-Home-on-Mac-computers

Good Luck!

I too found a conflict b/t Sophos AV & Time Machine on Big Sur. Its implementation is substantially diminished in terms of its features, and I don't think it is ready for prime time on Big Sur. So I've uninstalled it from all my Big Sur machines as well.

That has got to be complete bunk! Without Sophos AV I'm Time Machining 4 Big Sur machines to my Synology RAID NAS without issue. Did Apple just chuck all their Airport Time Capsules out the window? Of course not, and their 11/12/2020 notes 3 of the 4 options for backup as being SMB remote to the subject machine (https://support.apple.com/en-us/HT201250). That "senior" support rep is just someone who doesn't know what they're talking about.

This is from the latest Big Sur support page on Sophos:

• Time Machine backups to NETWORK locations are currently failing when Sophos Home is installed on Big Sur macOS 11 - This issue is currently under investigation by our development team. 

I've been through this pain beginning with Catalina. I have tried all the suggestions on all the posts I found. I can no longer back up to NAS (Synology). It worked great with prior MacOS versions. I've been through deep dives with Synology ("talk to Apple"), and with Apple ("talk to Synology"). A further escalation with Apple (they were very responsive, but the answer is not satisfying) was "per Apple software engineering we no longer support NAS with Time Machine". I was hoping that Big Sur would have a different outcome, but reading this thread would indicate otherwise. Really disappointed in Apple on this one.

Yes, I've seen other postings mention having to tweak settings on Synology boxes to get it to work. On WD My Cloud, when I set up the box for Time Machine, it automatically turned on AFP with no other options. If I turn off AFP, it resets the box to not be visible to Time Machine. Very simple.

rolandwartenberg wrote:

Good article covering this topic at https://eclecticlight.co/2020/06/29/apfs-changes-in-big-sur-how-time-machine-backs-up-to-apfs-and-more/ ... I have the same problem as I upgraded one of my MBPs to Big Sur today :-(

This does not relate to Synology backups which are network backups and not using either APFS or HPFS volumes. It is more like a local process related to anti-viruses on the Mac is blocking Time Machine in creating a remote backup.

Hi,

I meanwhile tested successfully that AFP on an upgraded Big Sur system (from Catalina) is still working whereas it's not anymore on a fresh installed Big Sur (which I did the other day as a test). Looking at other articles like https://www.synoforum.com/threads/mac-os-big-sur-drops-afp.4717/ I will now set up a complete new backup set on my NAS using SMB.

Best

Roland