Target disk mode, Big Sur error

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Level 1

9 points

Target disk mode, Big Sur error

Early 2015 MacBook Pro

I have downloaded and started the installation of Big Sur. After i clicked to install, MacBook showed the message that the memory was almost full (so I couldn’t do anything about it).

Then it went to installation and showed an error: “An error occurred preparing the software update”. And then kicks me

into Target disk mode. I don't have another computer to connect.

Currently just tried to reset SMC and use safe mode (as suggested by Apple Advisor). Both keep getting me back to the installation screen and waiting time. It’s basically running in a loop. The last time i tried the safe mode, it just froze on the last minute.

How do i stop the loop? Is there any way to stop the installation at all and get back?

MacBook

Posted on Feb 2, 2021 3:19 PM

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Answer 1

a brody

Level 10

83,929 points

Feb 2, 2021 3:32 PM in response to dana656

Not 100%. The best thing you can do is shut it down, and put into target disk mode to attempt to rescue all the files off of it.

You need a minimum of 35 GB of continguous space to install Big Sur,. That means if you have deleted a lot of big files your 35 GB free may not be enough unless that's the purgeable space.

If you only have 128 GB of storage on your computer, I recommend offloading all your videos, photos and movies onto two separate external drives. Any large amount of backup storage to iCloud will run out of space if you have that enabled on such a machine.

Use Devon Technologies EasyFind to locate as many big files as you can so the machine has at least that much purgeable space free.

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Answer 2

dana656 Author

Level 1

9 points

Feb 16, 2021 7:09 AM in response to a brody

Okay, so it took me a while but i managed to find another newer Macbook Air 2019. My question now is, how do I connect them? My theory is to buy thunderbolt 2 cable and thunderbolt 3 (USB-C) to thunderbolt 2 adapter and try to connect them. Is it the right cables? Or should I get something different?

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Answer 3

a brody

Level 10

83,929 points

Feb 19, 2021 5:08 AM in response to dana656

Not really. But if you do, you may be able to restore your documents to another Mac, or an external hard drive that is booted.

That's if your Mac is not secured under FileVault or the T1 or T2 chip on some Macs is not enabled.

Always backup your data before installing anything. And read specs carefully. You need 35 GB of contiguous space free for Big Sur. Anything less is not enough. Fragmenting on small drives of 128 GB makes this really difficult to achieve.

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Target disk mode, Big Sur error

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