iMac 27" 2020 update failed


Hi i got an imac 27" 2020 in with failed update (from catalina to Monterey)

turn on yellow screen

I started in Transfer Mode and made a backup from the data
then started DFU Mode and made a reset, after that i started with alt and "R" and got Catalina installed, normaly running seems all ok

I started the Update for Monterey and got the same result like my client, a yellow screen ( after the apple and about 2:30h installing)

now, starting with "alt" and "R" it is not possible catalina to install, only Monterey, so that means for me the bios is new flashed also

I attach a file with the yellow screen, only cursor is to see

I just now have no idea what this can be



Staff member
"Option-Shift-Command-R: Start up from macOS Recovery over the internet. Use this key combination to reinstall the version of macOS that came with your Mac."


thanks, that is working, so far so good, but how to update the machine without problems? what would you suggest?


is this yellow screen a possible faulty RAM or ssd? the catalina is working without any problem.
Maybe the 12.5 has problems?

I try now to install the 12.4 from usb stick


12.4 installion from usb stick
same problem, after installation cames the apple and the about 25% of the loadbar, after that it is switching to the yellow screen, the cursor is possible to move

i tryed with all 4 rams one by one but the same

i tryed an working 12.4 installation from external disk, same problem

i have no idea, this is a 2020 imac, should be able to update isnt it?
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i coulnt fount any matching warranty programm and yes for this client its important to update this machine.

is there no way?


yes, I did both and after that i tryed to install Monterey but everytime I get the yellow screen
Installing Catalina is no problem