Catalina auto-update completely wrecked 2017 MBA.


macrumors 6502a
Original poster
Jan 5, 2011
This is my Mom's computer. Auto-updated to Catalina today. About 80% of the way through the install it froze, then crashed to an error log and an option to restart or shut down. Tried to restart, got the black loading bar then it froze and failed the same way. I offered to help and held Alt and tried to select Macintosh HD to boot from, but just got the "no" symbol. Opened recovery and did a disk repair, nothing. Opened recovery again and tried to reinstall Mojave from scratch. That time the Mojave install failed in the same way. Downloaded Catalina on my laptop and made a bootable USB. Tried that and it failed to install from the USB stick.

Looks like the only option is to do a complete erase, repartition, and reinstall but I'm not even 100% sure that will work. She has un-backed up files on there which I was trying to recover but there doesn't seem to be a way. I booted the laptop onto an external Ubuntu USB drive but even from Ubuntu I can't access Macintosh HD (probably because Filevault is on by default?)

All I can say is wow - I've never seen a laptop fail this badly when user error wasn't involved.


macrumors regular
Jun 16, 2015
Portland, Oregon
You might be able to salvage the un-backed-up files using Target Disk Mode. You don't say what model year MBA your Mom has, but likely it has the Thunderbolt port. If so, and you have a Thunderbolt port on your 2012 MBA I believe, you can connect the two together and have your Mom's internal storage show up on your MBA as an external disk (you'll need to supply the Filevault password).

The only thing is that Thunderbolt cables are still somewhat expensive.

The other thing I would try is to prepare an external disk with a MacOS Mojave install, and see if her computer will boot from that via USB. If it does, then you should be able to access the internal disk once you supply the Filevault password. This all assumes she doesn't have a very late model MBA with the T2 security chip, which could make both of these approaches problematic.
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