2009 iMac Restore Issues

My notes...

Use the Recovery Partition — Starting with 10.7 Lion, which was sold only through the Mac App Store, the installer disc was replaced by the Recovery partition, a small chunk of the boot disk that contains a stripped-down version of Mac OS X and essential utilities. To reset the administrator password when running Lion or later:

1. Restart the Mac while holding down the Option key, and double-click the icon for the Recovery partition. A Mac OS X Utilities screen appears.
2. Choose Utilities > Terminal.
3. In Terminal, type resetpassword. Rather unusually for a task performed from the command line, a graphical Reset Password window appears.
4. Select the startup volume at the top of the window, and then choose a user account from the pop-up menu. In the fields below, enter the new password, confirm it, and add an appropriate hint.
5. Click Save, and then choose Restart from the Apple menu.

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.

https://discussions.apple.com/thread/254793247?answerId=258936149022#258936149022

Clean Install of High Sierra: Multiple Fa… - Apple Community

https://discussions.apple.com/thread/255040953?answerId=259391356022#259391356022