TerraMaster Forum

I have an F4-425 running TOS 6.0.794-01324
I have three Macs, which previously have been backing up to the TimeMachine service (Bonjour/SMB) without issues.
I upgraded two Macs to OS 26.2 (the latest version of Tahoe) and since then the backups fail on these two Macs

Looking at the Mac's Console log, I see the backup starts, and then gets:
BGSync: Client Has No Connected Transports
At which point the backup fails.

I have tried connecting the Macs and the F4-425 via a wired connection to the same switch, eliminating any network issues as the cause.
I can confirm that both Macs will backup as expected to an external hard drive connected via USB, eliminating TimeMachine as the cause of the issue.
I have tried deleting the sparsebunde folders on the F4-425, and setting up the TimeMachine sync from scratch, but neither Mac is able to complete the initial backup -- again, the process fails with BGSync: Client Has No Connected Transports
The third Mac, still running Mac OS 13.6.9, continues to backup successfully, automatically, every night, as expected.
There is plenty of free disk space on the Macs, and on the F4-425.

Is anybody else experiencing problems with TNAS, TimeMachine and OS 26?

It's a strange phenomenon. We're sorry you've encountered this issue. We have not yet observed other similar cases.
Please confirm whether you can directly read, write, copy, and paste files on the SMB network drive on these two Macs with the anomaly? (To determine if the problem is related to SMB or only to Time Machine)
Perhaps you could simply try modifying the minimum SMB version on the NAS.

Hi, sorry for the delay, but I have been experimenting.
Yes, both Macs can use go->contact to server to successful mount any shared folder in the F4-425 (for example smb://DaisyDisk.local/Jon)
Thay can both read and write successfully to the mounted folders.

After advice from TNAS support, I turned off the 'veto' checkbox in the SMB share setting on the F4-425.
This partially worked.
Both Mac were able to complete a first backup overnight, and one (set to once-daily) has been able to make a second nightly backup.
However, the one set to hourly backups is unable to complete any subsequent backups.

Interestingly, the hourly backup seemed to want to upload many tens of GB of data, over the course of several hours, even though there had been no changes to the files on the Mac since the initial backup. Could it be something to do with it?