Time Machine, shared drives and Mojave

For many years, I ran Time Machine on my MacBooks to a NAS, but over time (and MacOS releases!) that became less and less reliable, so I instead started backed up to (an external drive on) a Mac mini running the Time Machine server part of OSX Server. As functionality was progressively stripped out of OSX Server, I have stopped using its Time Machine Server, shared a drive using normal file sharing, and used that as the Time Machine destination instead.

Whilst that Mac mini was running El Capitan, that worked fine, even when I upgraded my MacBook to Mohave. However, I have now also upgraded the Mini to Mojave, and now I find that it I can no longer get it to work as a Time Machine destination. Whenever I try to run a backup I get this message:

Time Machine couldn’t complete the backup to “.local”.

The network backup disk could not be accessed because there was a problem with the network username or password. You may need to re-select the backup disk and enter the correct username and password.

Needless to say the username and password are both correct! The advice in the Apple knowledge base is useless. I have done everything I can think of, re-selecting the drive as the target disk, erasing and re-creating the keychain for that disk, and even completely re-formatting the shared drive, but cannot get past this error, and I’m now getting very frustrated - Time Machine backup to networked locations has been my way of working for almost a decade now, and is essential for laptops, but Apple seem to have been intent for several years now on making it more and more difficult! Has anyone any suggestions here?

I know that Time Machine has been changing. In Mojave, “If you’re using APFS, local snapshots are created on your APFS disk, regardless of whether the disk is on a portable or desktop Mac.” In Catalina, the backup extension changed from .sparsebundle to .backupbundle and the TM backup cannot be used to recover a file on a non-Catalina Mac (using the normal procedure).

I’ve had my own problems with Time Machine. After I upgraded my 2018 mini to Catalina Time Machine backup (SSD to SSD) became ridiculously slow (hours to backup 10 GB). I gave up and switched to ChronoSync for local backup.

If you want to stay with TM, I’d suggest connecting it directly to your MacBook. Personally, I no longer trust it.

And, as is so often the way, no sooner had I posted that than I saw the solution!

When upgrading the Mac Mini, because I was also re-structuring it I had also changed its name from “Theodore” to “Theodore II”. I changed the name again, to “Theodore-II” (no space!), and it is now backup up quite happily!

I’m not yet ready to go to Catalina - I’ve too many machines doing too many different things, and I can’t afford to screw up stuff that is working now. But I’m also not ready to move to backing up only to direct-connected media: that pretty much negates the whole point of a laptop!

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I usually wait until x.4 of a new macOS version to upgrade, so I would normally upgrade at this point, but I think I’m going to wait for another few weeks. Mojave 10.14.6 is working well for me.

I agree.

A few years ago I had problems with Time Machine being unable to backup one of my executive’s MacBook Pro. His photo library was so large TM could not complete a backup while he was in the office. The solution was ChronoSync running on his Mac and ChronoAgent running on one of my utility Macs in the server room.

Econ Technologies has a 15 day free trial. Might be worth a look.


Thanks - I’ll bear that in mind for when Time Machine finally lets me down!

Also use SMB rather then AFP protocol. Apple had been deprecating AFB…