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Reinstall High Sierra on 2009 iMac

I have a 2009 iMac which was in my son's possession. Somehow the OS was wiped clean. I'm trying to reinstall High Sierra and have created a bootable disk on a flash drive. When it comes time to select the drive for installation, the only choice given is the flash drive disk...which says "this disk it is locked."

iMac 27″

Posted on Jan 13, 2023 3:37 AM

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Posted on Jan 13, 2023 5:40 AM

Go a few steps back. Boot from the usb drive, but select disk utility first. After that follow this instructions to see if you can repair your disk


How to repair a Mac disk with Disk Utility - Apple Support



I had this also with a 2009 iMac, what helped me was to plug in an external hard drive and install high Sierra on that one. When it was installed, I opened disk utility and I could re mount my internal drive. So if you don't see your internal drive in above steps or you cannot re-mount it, you can try that as last resort

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Question marked as Top-ranking reply

Jan 13, 2023 5:40 AM in response to onilvehs

Go a few steps back. Boot from the usb drive, but select disk utility first. After that follow this instructions to see if you can repair your disk


How to repair a Mac disk with Disk Utility - Apple Support



I had this also with a 2009 iMac, what helped me was to plug in an external hard drive and install high Sierra on that one. When it was installed, I opened disk utility and I could re mount my internal drive. So if you don't see your internal drive in above steps or you cannot re-mount it, you can try that as last resort

Reinstall High Sierra on 2009 iMac

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