Migration assistant doesn't recognise an apple time machine back up on an external disk

Hi ZillaB

This at least might start some discussion on ways or not.

My guess is that TM backup is not recognised for although physically the same computer with the much new operating system and probably a new name for the computer it thinks it is completely different. So migration assist on TM or TM Star Wars won’t work.

I have three suggestions:

1. You should be able to open the TM backup as you would a normal folder and drag and drop various files across to the Mac.

2. If you have a bootable backup of the original system you could try to boot your Mac with that then erase the internal hard drive along with OS 12.2, formatting as Mac Extended Journaled.

Then using say Carbon Copy Cloner (or similar) copy the bootable backup onto the Mac hard drive.

When finished restart into the mac directly.

If that wasn’t as up to date as the TM backup then TM backup should be recognised if your bootable backup is the same ‘computer’ in all respects as the TM backup.

Download 12.2 then either upgrade to 12.2 directly or take it up in stages.

NB the 10.14 version (Mojave) probably used 32-bit software whereas 12.2 will not, so whole other can of worms

3. I doubt the following will work but …:

Boot the 12.2 mac into recovery mode

Erase the hard drive and format it Mac as Extended Journaled then use the time machine backup to restore.

Upgrade if you wish to 12.2

Hello ZillaB,

We understand you're unable to restore data to the iMac with an existing Time Machine backup. We'd like to share a resource that may help: If you can't back up or restore your Mac using Time Machine

Best regards.

Let start with your second reply as it is ‘simpler’

If you have the time then you could try to copy to APFS drive but I very much doubt it will work. As you still have the same problem that your new formatted mac is not the same as the TM mac.

Up to Big Sur TimeMachine had to be on Mac Extended Journaled drive and as your TM is before Big Sur I don’t believe it will work if you put on an APFS drive.

But if you wish to try then copying a TM backup is not simple.

The best way is to use SuperDuper but it will erase/format the target drive which in your case doesn’t matter. I recently copied a 360GB TimeMachine drive that took 9 hours and 23 minutes so be prepared to keep everything turned on for a longgggg time.

To your first reply:

"do you know what files are transferred during a migration assistant set up?"

From memory you can choose what to copy eg Applications, Individual Users , settings …. All or some of the above.

I have used Migration Assist but I mostly use Carbon Copy Cloner if I want to copy a system from one device to another.

You have suggested various ways to copy data across and as long as you are not going to destroy systems, without an ability to recover, then give it a try.

Which leads me to very important topic make sure you have a back up of your target preferable a bootable copy. Though I believe even Carbon Copy Cloner can’t make a bootable copy of 12.2. So if you are likely to destroy the target have a strategy to recover eg can you take back to Apple Store?

Again I do not believe you will be successful using migration assist unless you get the Mac back to where it was at the time of

timemachine backup.

I return to suggestions 1, 2 and 3.

Sorry correction for 2 & 3, as you will be starting with Mojave (10.14) and want to upgrade, format the mac hard drive as APFS