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User profile for user: Alec552
Alec552 Author
User level: Level 1
4 points

Monterey update bricked 2015 iMac

 My 2015 iMac was set for auto-updates

Two days ago it performed a Monterey update. No errors but now it won't boot. Goes to the "prohibited" screen

Disk utility shows the drive is intact, but "writeable" is set to "No"

Option to download Sierra OS hangs at the point where it asks for drive volume. No options are given.


In the "compatible device"s list for Monterey the 2015 iMac is not listed.

If so, why did auto-updates allow this to occur?


Can this be fixed?

iMac 27″, macOS 12.6

Posted on Sep 19, 2022 11:06 AM

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User profile for user: Old Toad
Old Toad
User level: Level 10
210,615 points

Posted on Sep 19, 2022 11:53 AM

See if this Apple document helps: if your Mac starts up to a circle with a line through it


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User profile for user: Alec552
Alec552 Author
User level: Level 1
4 points

Sep 20, 2022 8:19 AM in response to Old Toad

Apple document is no help

Cannot reinstall OS as it apparently does not have write access to the drive. Maybe a permissions problem.


Tried booting from a memory stick. Boots fine but no access to hard drive probably because of security settings.


Seems to be no way to get to the data off the drive. Any suggestions welcome.

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Monterey update bricked 2015 iMac

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