Bootable Installer for iMac 2012

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Bootable Installer for iMac 2012

I have an old iMac (2012) that was completely wiped. When turned on it only shows a white screen with a "🚫". After entering internet recovery mode I was unable to reinstall MacOS as I am getting an error that says my system does not support this version of OS. After some researching on how to get around this error, as I am very new to this level of administration and using Terminal, I am trying to create a bootable installer on a USB drive. I am trying to use a 2021 Mac book Pro to do this, running Ventura. I have treid with Sierra, El Capitain, and Yosemite, but cannot seem to get the installer drive to open, so that i can access the installer application (in order to run the command in terminal provided by apple, example ;;; sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app)

I have tried manually opening the pkg. with terminal and creating a file for it in applications, but to no avail. Not entirely sure how to progress so i can reinstall macOS and get this computer working. Any ideas..

Posted on Jan 27, 2023 3:02 PM

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Answer 1

Best reply

John Galt

Level 10

141,676 points

Jan 28, 2023 10:17 AM in response to Jessmeadows19

Thanks for the additional information. A 2012 iMac would have shipped with OS X 10.8.x "Mountain Lion", and if its startup disk had been completely erased that is what it should offer to reinstall.

Boot Recovery using the following key chord, as described in Use macOS Recovery on an Intel-based Mac - Apple Support:

Option-Shift-Command-R: Start up from macOS Recovery over the internet. Use this key combination to reinstall the version of macOS that came with your Mac or the closest version that’s still available.

The startup disk must first be formatted Mac OS X Extended (Journaled) as a prerequisite, so when the OS X Utilities screen appears, choose Disk Utility. You should not be confronted with an error since the disk is not mounted in Recovery mode.

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Answer 2

John Galt

Level 10

141,676 points

Jan 28, 2023 5:51 AM in response to Jessmeadows19

When starting a Mac from Recovery, the startup disk is not mounted: Use macOS Recovery on an Intel-based Mac - Apple Support. Scroll down to Erase and reinstall macOS.

Step 5 will not offer APFS as an option. Choose Mac OS X Extended (Journaled) instead.

Step 7 will not offer to reinstall macOS Ventura. It will probably be El Capitan instead, but the steps are otherwise the same.

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Answer 3

Jan 27, 2023 3:07 PM in response to Jessmeadows19

Just a note i left out, I have tried to repair the disk with first aid, and i did try erasing it and ensuring it was formatted correctly. However, I am also getting an error that says the disk cannot unmount, when I choose to erase it.

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Answer 4

John Galt

Level 10

141,676 points

Jan 27, 2023 4:26 PM in response to Jessmeadows19

Creating a "bootable installer" is not required and attempting to make one just going to introduce complexity and increase the likelihood of error.

Start from the beginning. You wrote that you "completely wiped" that Mac's original startup disk. That must be accomplished by booting macOS Recovery, and the startup disk needs to be formatted Mac OS Extended (Journaled) before you can reinstall its originally installed operating system.

Did you do that?

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Answer 5

Jan 28, 2023 1:18 AM in response to John Galt

Yes I have booted macOS recovery, and tried formatting the disk. However, I am getting an error that says the disk cannot unmount, when I choose to erase it. I have tried repairing it with the first aid and it doesn't resolve the problem.

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Answer 6

Jan 28, 2023 9:29 AM in response to John Galt

The imac is from 2012. I am unable to reinstall Sierra in the recovery mode because it gives me an error, saying the computer is not compatible with this version of macOS. I know this is not the case, however, to resolve the problem I have tried following the steps outlined in the "Erase and reinstall macOS". When I get to the step to hit continue and erase, it gives me an error and "cannot complete". If i look at the details portion of the error, it says "cannot unmount disk". I have tried repairing the disk with first aid and partition but none of this has shown to help.

This is why I was trying to use a bootable installer. I dont know what else to try to get around this error message in reinstalling macOS.

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Answer 7

Jan 30, 2023 7:21 AM in response to John Galt

It doesnt seem to offer mountain lion. I booted in macOS Recovery over the internet, via Option-Shift-Command-R. I am still unable to format the disk, it continually provides an error.

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Bootable Installer for iMac 2012

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