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

Reply

Answer 1

Top-ranking reply

OtherWeather

Level 1

18 points

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.

Reply

Answer 2

HWTech

Level 9

60,452 points

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.

Reply

Answer 3

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

Reply