2

Every year or so I like to do a fresh install of Mac OS on my machines. The method I've always used is to download the OS from the App Store, create an installable USB with Terminal, boot into the USB, format the internal storage and then install.

This has not worked on my most recent Mac, which is a 2018 Intel Mac mini (the only one I have with a T2 chip). It first wouldn't let me boot into the USB due to a security restriction, so I rebooted into recovery mode and formatted the internal storage there. Before restarting I attempted to restart to the USB with Target Disk Mode, but it wouldn't pick up my USB within about a minute of waiting (maybe I should've waited longer) so I just restarted it normally and tried once again to boot to the USB on startup.

Every time I select the USB device on startup, it falls back to internet recovery mode. The yellow USB drive icon just instantly turns into the globe and prompts me to connect to WiFi. I've tried this method a few times but it sounds like any blip in the connection causes it to give up, and this has happened to me 4 times now. Is there any reason why a T2 Mac with no OS would not boot to a USB device? Is there anything else I can do besides retry internet recovery until it finally downloads everything in one go?

Thanks!

UPDATE: I did eventually get Internet Recovery working. See my answer below

Improve this question
6
  • I would say that there is very little point in doing a fresh install every year, particularly if you then restore all your user settings and everything else. What little benefit there might be can be achieved more easily with other methods, with less time, effort and risk.
    – benwiggy
    Commented May 2, 2021 at 10:31
  • 1
    I've been using macOSX since the public beta, and I have never done one of these (so called) clean installs. They are an unnecessary routine and needful only if macOS has a serious issue that requires it, otherwise you are wasting time and energy. This may be a holdover from Windows that does need a reinstall from time to time but macOS is not Windows.
    – Steve Chambers
    Commented May 2, 2021 at 12:01
  • @benwiggy & Steve - I wasn't going to mention it, but I actually have line-of-sight migration from the first Mac I ever used at home rather than just at work. 2001. No clean installs. [Quite often literally lifting the boot drive from one Mac to the next, whilst that was a simple task - mainly Mac Pros through the years] There is the hint in the OP that the Mac is being treated like Windows, with its 'inevitable bit-rot'… except the one WinPC in the building is also line-of-sight back to mid 2000's, so that's not true either
    – Tetsujin
    Commented May 2, 2021 at 17:29
  • @Tetsujin Yes, I've probably got 'cruft' from my Panther G3 iBook on my Big Sur Mac Mini...!
    – benwiggy
    Commented May 2, 2021 at 18:06
  • @benwiggy - by mid June I'll have Bondi Blue iMac to M1 iMac in a straight line… though I'm wondering what I'm going to lose in this latest transition :\ [I'll still have the old Mac Pros though]
    – Tetsujin
    Commented May 2, 2021 at 18:19

3 Answers 3

Reset to default
2

Ahhh… Catch 22 mistake, I'm afraid.

You can't boot to USB with Secure Boot on & you can't toggle Secure Boot settings without an admin account, which was of course erased when you formatted.
You will need to use Internet Recovery to get back to a state you have an admin account, or take a trip to an Apple Store, with proof of purchase.

See Apple KB - About Startup Security Utility

Improve this answer
3
  • 1
    I had an inkling it might be something like that. Lessons will be learned. Thanks for your help! I'll try using ethernet......
    – Ben Cheshire
    Commented May 2, 2021 at 10:28
  • I've took mine to Apple store and later on they've called me asking for my iCloud password to remove activation lock. Asked if I can do myself without sharing password to which they said to go on Find My app/website and remove it from there after which it worked, but I don't know what else they did.
    – Dzh
    Commented Mar 14, 2022 at 1:37
  • TLDR: try removing it from Find My app or website.
    – Dzh
    Commented Mar 14, 2022 at 1:37
2

I did eventually get Internet Recovery working. I was getting various errors (-1008F, -2106F and perhaps others) after long periods of time spent waiting for the boot to complete. While some of these may have been down to a shoddy internet connection, it seemed as if it would just error immediately after the bar had reached 100%.

After doing a bit of digging I removed the Mac from my iCloud account via appleid.apple.com as well as perform all steps on this guide to restore a Mac with Apple Configurator 2 (I found about that on this thread). You will need an additional Mac on hand to do the latter.

After doing that, then booting with Internet Recovery and then reinstalling from the recovery menu I still needed to log in using my iCloud credentials as well as my old local account. Fortunately for me that wasn't a problem at all, but bare that in mind if anyone reading is in a similar situation!

Improve this answer
0

Do you have another Mac? You can still use Target Disk Mode on these Macs, without any security problems. So you may be able to install an OS or restore a backup that way.

Once you've got an OS on the disk, there may be an extra step to get the admin user recognised by the Recovery Partition, so you can alter the Secure Boot settings.
See my answer here: "No administrator was found" in Startup Security Utility

(I have one of these Macs, and I disabled Secure Boot the minute I got it.)

Improve this answer
1
  • Thank you very much for your suggestion. I was eventually able to reinstall using internet recovery. Had that not worked I would definitely have given this a go.
    – Ben Cheshire
    Commented May 2, 2021 at 22:11

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .