Reinstall Big Sur with bootable disk

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Reinstall Big Sur with bootable disk

My wife upgraded to Monterey but some of her niche software is not compatible, so we followed tutorials on downgrading to Big Sur. We created the bootable disk, erased the startup disk, inserted the startup disk, start up pressing Option. We are given the option to Install Big Sur from the startup disk. We click that, it then asks for wifi. We select the wifi, enter the password and it that displays a spinning globe with text "Starting Internet Recovery". This goes for a while with the progress bar progressing, but then get the error 100f and it stops.

We have tried four times, the wifi is reliable and the bootable disk is still connected. It seems to get to the end of the bar and then the error appears.

Can anyone make any suggestions please?

Thanks

Posted on Jan 31, 2022 2:32 AM

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Answer 1

Best reply

HWTech

Level 9

56,990 points

Jan 31, 2022 7:34 PM in response to candell19

Did you ever modify the Startup Security Utility settings from Recovery Mode to allow booting from USB? If not, then you may not be able to do that if you already erased the SSD. If USB booting is not already enabled, then you can try booting into Internet Recovery Mode (Command + Option + R) to see if you can enable USB booting now:

About Startup Security Utility on a Mac with the Apple T2 Security Chip - Apple Support

If you cannot enable USB booting, then you may need to reinstall macOS from Internet Recovery Mode so that you can then enable USB booting so you can boot the Big Sur USB installer. Or you can boot into Internet Recovery Mode using Command + Option + Shift + R to boot to the installer for macOS which originally shipped with the laptop from the factory, after which you can download & run the Big Sur installer to upgrade the older macOS.

Try connecting the laptop directly to the router using an Ethernet cable and a USB-C to Gigabit Ethernet Adapter for a faster more reliable network connection which bypasses any hard to troubleshoot WiFi issues.

If you have a 2018+ Mac, then you may need to "Restore" the firmware:

Revive or restore an Intel-based Mac using Apple Configurator 2 - Apple Support

Revive or restore a Mac with Apple silicon using Apple Configurator 2 - Apple Support

FYI, you should have tested your USB installer before erasing the laptop since the USB macOS installer does include Disk Utility.

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Answer 2

candell19 Author

Level 1

15 points

Feb 1, 2022 2:07 AM in response to HWTech

Catalina also ran to the end and then displayed the error.

The Firmware restore procedure requires "A supported USB-C to USB-C charge cable". I tried the one that came with the MacBook with no luck, I tried a third party cable (charge and data) https://www.amazon.co.uk/gp/product/B083Q9D99D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 but that also displays the same message as the official cable "Connect accessory using a thunderbolt capable cable".

Is there a specific cable I need such as this one - https://www.apple.com/uk/shop/product/MQ4H2ZM/A/thunderbolt-3-usb%E2%80%91c-cable-08-m?fnode=5a67bb12c9522907a9bb5e0b864479064b9f32d48ee17dcccf157414c592af57e0e670add3fe95cb3fc70821d4593b878fc8a07a3294acb40399d16d5ffb8d0e52ce64d06a1449a19a6cdd97fb68942117c4fe36dcd81e71ce5cb5948c464775

BTW, the Macbook with the issues is a MacBook Pro (13-inch, 2018, Four Thunderbolt 3 Ports), the healthy Macbook using to restore is a 13-inch 2020, Two Thunderbolt 3 ports)

Thanks again

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Answer 3

candell19 Author

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15 points

Feb 1, 2022 1:16 AM in response to HWTech

Thank you for the reply. I enabled USB booting and checked the setting to confirm, but it certainly doesn't seem happy. It is a T2 2018 MacBook, I have just created a Catalina bootable USB and am currently giving that a go. When I start up the machine pressing Option, it does recognise the media, when I click it, it then asks for the wifi password.

If Catalina doesn't work, I'll try the firmware restore, thank you for the suggestion. I do have a USB-C to Gigabit Ethernet Adapter somewhere, will dig that out also.

Thanks

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Answer 4

HWTech

Level 9

56,990 points

Feb 1, 2022 5:09 AM in response to candell19

The USB-C charging cable that ships with the laptop will work as I have used that multiple times with our organization's 2018+ Macs. Make sure you connect the USB-C cable to the front left port of the laptop that is in DFU Mode which you want to restore. If that does not work, then you should have Apple or an Apple Authorized Service Provider examine the laptop and assist you. If there is a hardware issue with the front left USB-C port, then the procedure will not work.

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Answer 5

candell19 Author

Level 1

15 points

Feb 1, 2022 5:41 AM in response to HWTech

I was using the front left, seems the local Apple repair store is the next port of call. Thanks for the replies.

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Reinstall Big Sur with bootable disk

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