Can't reinstall macOS after wiping MacBook Pro 2018

Question

Can't reinstall macOS after wiping MacBook Pro 2018

Hi, can anyone help me with the issue? I'm having with my 2018 MacBook Pro.

I erased it following the instructions on the Apple website, but I can't reinstall Mac OS. Either with Internet recovery or a bootable USB drive

Every time I try, I get the following message. Security settings do not allow this Mac to use an external startup disk . You can change this by restarting and holding down Command-R to open macOS Recovery and then choosing Startup Security Utility. internet recovery just doesn't work it just does nothing

I contacted Apple support via live chat, and they suggested formatting the drive again with Disk Utility, but it wouldn't do this .it came up with an error.

So they said that the drive could possibly be faulty so they couldn't help me any more. And it's a vintage Mac, but I could possibly take it for service.

Afterwards, I decided to try running an Apple diagnostic and that didn't give any errors at all

One idea I've had could it be the T2 chip security settings?

I did try DFU mode with another Mac connected to restore the firmware but didn't have any success

I don't live near an Apple Store or a third-party Apple repairer, and it's not really worth spending anything on this Mac I just wonder if there's anything else I could try at home

thanks

oliver

MacBook Pro 15″, macOS 12.7

Posted on Nov 17, 2024 1:36 PM

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Answer 1

Top-ranking reply

HWTech

Community+ 2026

Level 9

70,250 points

Nov 27, 2024 6:52 PM in response to oliverfromhalesworth

oliverfromhalesworth wrote:

I'm still having trouble getting it to boot to a USB

On a T2 Mac, you need to first modify the security settings to allow booting from USB by using the Startup Security Utility:

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

I'm not really sure how to use Apple Configurator

I'm not sure what you are trying to do with Apple Configurator. Here is an Apple article regarding the DFU firmware Revive & Restore which can use Apple Configurator (or with later versions of macOS the Finder can do it instead):

How to revive or restore Mac firmware - Apple Support

Here is an Apple article regarding Apple Configurator:

Apple Configurator User Guide for Mac - Apple Support

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Answer 2

Nov 27, 2024 1:16 PM in response to oliverfromhalesworth

I've managed to solve the issues with my MacBook Pro not booting

I managed to borrow an old Mac from a friend. Actually, it was my old machine that I gave him a few years ago, a very old mid-2010 MacBook Pro.

I had tried everything different bootable installers and target disc mode from another Mac, which didn't seem to connect for some reason. It could've been the cabling or something; I'm not sure.

The last two ideas I had to try before giving in were to do a Time Machine backup of the mid-2010 machine and then try and restore that data to the 2018 MacBook Pro I was having the issue with

The other was to make a bootable USB from the older machine instead of my Apple silicon Mac, as I had been doing previously thinking, that maybe with them both being intel machines it may work better.

So, I set the backup process to a spare external hard drive while I was waiting for that, I downloaded macOS High Sierra and made a bootable USB drive

I decided to try the Time Machine backup first, after starting the 2018 Mac in Internet recovery, I selected the restore from Time Machine backup option.

It went through the process, formatted the SSD, and then proceeded to install the data from the backup I'd made from the other machine, and I was at the login screen with everything working pretty quickly

I then updated to Mac OS Sequoia and then erased all content and settings. this time, everything went smoothly, and I was soon presented with the set-up screen like a new out-of-the-box Mac

I'm not sure what the issue was. I'm glad to have it fixed

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Answer 3

Nov 17, 2024 2:36 PM in response to oliverfromhalesworth

Yeah, with Intel Macs you have to change that setting to boot from a USB. If you cannot change that setting then you're stuck with internet recovery. If internet recovery isn't working, you'll have to use Apple Configurator to reinstall the recovery OS. For fun though, select "Apple SSD..." and try formatting from there and see if that works.

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Answer 4

Nov 19, 2024 12:42 PM in response to oliverfromhalesworth

With the 2018-2020 Intel Macs with T2 security chip.....once the internal SSD has been erased you will not be able to boot from USB until you install macOS through Internet Recovery Mode so that you have a valid macOS admin user account on file with the T2 security chip. The T2 security chip uses the list of valid macOS admin users for authenticating before you can modify any system security settings such as allowing booting from USB drives.

If you had enabled booting from USB prior to using Disk Utility to erase the internal SSD, I'm not sure whether you would still be able to boot to USB after erasing the internal SSD. I've never tried it. I do know that if you use the DFU firmware Restore that all previous settings are destroyed so Internet Recovery Mode is the only option to reinstall macOS the first time after the DFU Restore.

If you have access to another Intel Mac which is compatible with an OS this 2018 laptop can support, then I guess you could try putting this laptop in Target Disk Mode & trying to run the macOS installer from the other Mac to install onto the laptop that is in Target Disk Mode. I would go with Internet Recovery Mode (Command + Option + R) first since that should be the easiest option.

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Answer 5

Nov 18, 2024 5:11 AM in response to OtherWeather

thanks

I've now managed to format the SSD in disc utility

I'm still having trouble getting it to boot to a USB

I'm not really sure how to use Apple Configurator

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Answer 6

Nov 28, 2024 9:12 AM in response to HWTech

it's all sorted now

I've looked at the articles you posted for future reference

thanks

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Can't reinstall macOS after wiping MacBook Pro 2018

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