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User profile for user: chofat934
chofat934 Author
User level: Level 1
7 points

Locked macOS, can't reinstall High Sierra

can not reinstall operating system because of locked disk

I I am having similar problems as many others, but I don’t see or understand fully the various solutions offered on the forum as applicable to my situation. 


My system: iMac 27”, mid 2010, last macOS— High Sierra, 10.13.6


I was intending to sell this iMac after wiping it & then reinstalling the OS. Everything went fine until I got to the screen which read: No connection to the internet. I forgot that the iMac had an ethernet port on the back, & that’s where I think things went wrong. I erased the OS X Base System, thinking I could use my install disc to reinstall the original Lion OS. Wrong. After that it always booted up to macOS utilities, where I repeatedly got OS X Base System is locked when I tried to reinstall High Sierra. I have tried several Mac startup key combinations, but all boot up to macOS utilities. A circular firing squad. I don’t know how to proceed at this point. The Apple Store support is not really worth it as my 2010 iMac is probably too old to be sold for more than the support costs. Somebody can probably use this iMac.


Any practicable help would be greatly appreciated. 

Posted on Dec 23, 2022 3:15 PM

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User profile for user: Jack-19
Jack-19
User level: Level 8
46,020 points

Posted on Dec 23, 2022 6:24 PM

OK, thanks for running through those steps! What's in Disk Utility now is what you want to see; OS X Base System as a separate disk image under "Disk Images".


Now, select the top-level "ST31000528AS Media" drive, click Erase, and make sure this information matches:

  • Name: Macintosh HD
  • Format: Mac OS Extended (Journaled)
  • Scheme: GUID Partition Map


Click Erase, then quit Disk Utility, and reinstall macOS High Sierra.


Jack

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User profile for user: Jack-19
Jack-19
User level: Level 8
46,020 points

Dec 23, 2022 6:24 PM in response to chofat934

OK, thanks for running through those steps! What's in Disk Utility now is what you want to see; OS X Base System as a separate disk image under "Disk Images".


Now, select the top-level "ST31000528AS Media" drive, click Erase, and make sure this information matches:

  • Name: Macintosh HD
  • Format: Mac OS Extended (Journaled)
  • Scheme: GUID Partition Map


Click Erase, then quit Disk Utility, and reinstall macOS High Sierra.


Jack

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User profile for user: Jack-19
Jack-19
User level: Level 8
46,020 points

Dec 23, 2022 10:12 PM in response to MisJaxon

MisJaxon wrote:

I'm having the same issue, I'm running Sierra... I followed all these steps and right before it finishes I get an error that says it can't be completed. Can you tell me why that might be happening?

Hello!


What year is your iMac? Did you startup with Command-R, Option-Command-R, or Shift-Option-Command-R?


Jack

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Locked macOS, can't reinstall High Sierra

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