I wanted to clean the iMac off, so my son could use it. I attempted to erase in disk utility and something went horribly wrong. Now I can’t even boot it up except in disc utility when I press command R during reboot. When I try to restore, it gives me an error message, or could not complete. Help I just want to reinstall High Sierra so my son could use the computer for fun.
To perform this action will require booting from a Bootable Installer.
The Bootable Installer can Only be performed on an Apple Computer
This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer.
Example : Bootable Installer of High Sierra would have to be done on a computer that Qualifies to run High Sierra .
Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.
1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.
2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive.
3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives.
4 - Choose the Upper Most Drive ( not the volumes indented and list below ).
5A - Formatting for macOS 10.13 High Sierra and below requires HFS Journaled with the GUID Partition Map
6 - Once that is done >> backup out of Disk Utilities and choose install macOS.
7 - Follow the prompts and it may automatically reboot several time.
8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.
1. Start up from macOS Recovery
Option-⌘-R
Upgrade to the latest macOS compatible with your Mac.
APFS won't work for Sierra, Sierra needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.
What has often worked for others is to use this Restore Method instead of CMD+r keys...
Option-⌘-R
Upgrade to the latest macOS compatible with your Mac.
2009 iMac High Sierra
