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Crashed while installing Big Sur

Hi- after trying to update to Big Sur on my iMac it stalled at less than a minute. Was there for over 2 hrs. Now I’m stuck on the start up disc screen it’s asking me to click target disc mode. What do I do?

iMac 27″, macOS 10.14

Posted on Jul 6, 2022 1:31 PM

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Posted on Jul 6, 2022 4:13 PM

If I am reading this correctly and please correct me if wrong.


The computer was running Mojave macOS 10.14 and attempted to upGrade to Big Sur - right ?


Predicated on above as correct - is the Drive formatted in the New APFS format or still using the HFS Journaled Format ?

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Question marked as Top-ranking reply

Jul 6, 2022 4:13 PM in response to SddawnH

If I am reading this correctly and please correct me if wrong.


The computer was running Mojave macOS 10.14 and attempted to upGrade to Big Sur - right ?


Predicated on above as correct - is the Drive formatted in the New APFS format or still using the HFS Journaled Format ?

Jul 7, 2022 6:41 AM in response to SddawnH

SddawnH wrote:

Yes was using Mojave iOS 10.14 when I attempted to upgrade. Crashed at “less than one minute” notification was stuck on it for 2 hrs. I shut down computer and when restarted it opened back up on to the screen that tries to open in safe mode. “Mac iOS start up” with an option to connect to another computer with a lightning cable. My daughter was able to get it back to the Upgrade to Mac iOS Big Sur and it ran through all the way to the “less than a minute” stage. Then I left it alone and in an hour it started to shut down and reboot repeatedly- never making it to the completion- I finally just turned it off.
i did not format the drive- it was formatted at the Apple factory. I’ve had the computer since 2016.

Q - " with an option to connect to another computer with a lightning cable "


A - This tends to indicate a couple of things and the first is the Internal Drive did not have the Required Empty Space .


ie: Empty Space Requirements specific to the Big Sur. Apple states 35.6 GB Empty Space but suggest 50 GB


A - The Second thing was, it was offering to Transfer files between two Mac computers using target disk mode. This may have allows the User ( you ) to move some Large Personal Files, documents, pictures, videos, music files on the problematic computer and thusly increasing the Empty Space on the problem computer.


A - Should those aspects be explored by you & daughter - the UpGraded from Mojave to Big Sur just may work


Jul 7, 2022 5:25 AM in response to PRP_53

Yes was using Mojave iOS 10.14 when I attempted to upgrade. Crashed at “less than one minute” notification was stuck on it for 2 hrs. I shut down computer and when restarted it opened back up on to the screen that tries to open in safe mode. “Mac iOS start up” with an option to connect to another computer with a lightning cable. My daughter was able to get it back to the Upgrade to Mac iOS Big Sur and it ran through all the way to the “less than a minute” stage. Then I left it alone and in an hour it started to shut down and reboot repeatedly- never making it to the completion- I finally just turned it off.

i did not format the drive- it was formatted at the Apple factory. I’ve had the computer since 2016.

Crashed while installing Big Sur

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