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User profile for user: Vaughan Willis
Vaughan Willis Author
User level: Level 1
49 points

OS X Base System locked

I've just replaced my Mac and, with online help, did things like disconnecting the old Mac from iCloud, Un authoring from iTunes, etc. Having done that I've erased the disk and am now wanting to install the original operating system (Mountain Lion, I think). I'm connected to the internet but when I get to the place where I click to install, the Install button is greyed out and the OS X Base System says "This disk is locked".


I've tried other online help but with no answers. I'd so appreciate it if someone could walk me through the process (I'm not that much of a guru).

Posted on Jul 6, 2019 3:27 AM

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User profile for user: MrHoffman
MrHoffman
Community+ 2024
User level: Level 10
125,429 points

Posted on Jul 6, 2019 9:50 PM

If you don’t see Disk Utility on the first screen of the installer either directly or via the Utilities menu, then you’re left to build a bootable installer on another Mac and use that. I’d probably download and use El Capitan or High Sierra for that. If you still have and can download an older release and wan t use that here, you’ll have to,web-search for the bootable build procedure for whichever old release you decide use. El Capitan is as far back as the current createinstallmedia tool is available.

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User profile for user: MrHoffman
MrHoffman
Community+ 2024
User level: Level 10
125,429 points

Jul 6, 2019 9:50 PM in response to Vaughan Willis

If you don’t see Disk Utility on the first screen of the installer either directly or via the Utilities menu, then you’re left to build a bootable installer on another Mac and use that. I’d probably download and use El Capitan or High Sierra for that. If you still have and can download an older release and wan t use that here, you’ll have to,web-search for the bootable build procedure for whichever old release you decide use. El Capitan is as far back as the current createinstallmedia tool is available.

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User profile for user: Vaughan Willis
Vaughan Willis Author
User level: Level 1
49 points

Jul 6, 2019 8:53 PM in response to MrHoffman

Hi MrH there is no option to format the internal storage device, even in greyed out options. Incidentally, I mentioned in my original post that wanted to restore to the Mountain Lion OS which is what was on there when I first purchased the Mac but the option that comes up is to install High Sierra and I can't install from a Time Machine Backup because I deleted that when I got my new Mac and ensured that all my files, etc., were copied across, deleting the backup I had.

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OS X Base System locked

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