Recently had to reformat the 3TB HDD in a 2019 27" iMac and reinstall the OS. I made a bootable Sonoma installer USB stick and booted the machine.
I formatted the HDD as APFS. When I tried to install Sonoma I got the error: "This volume is not compatible with this update."
I found I had to go back and format the HDD as APFS (case sensitive) in order to get it to install. I looked on Apple's requirements site and do not see this documented anywhere.
Can someone confirm that this is a requirement or did I just have something funny going on with this machine?
Note that the HDD did have an issue where it would no longer boot the machine so the drive may have issues. It formatted and tested normally though.
[image|3108640]
+
+
=== Update (10/29/23) ===
+
+
Just wanted to follow up with this.
+
+
It turns out this was a fusion drive machine. I had incorrectly assumed that the 3TB HDD was the issue and simply pulled it and replaced with a 2TB SATA SSD and did not remove the 128GB blade SSD (because I did not remove the logic board).
+
+
What finally clued me in was that the machine would randomly fail to complete the boot up even though it initially setup and installed macOS just fine on the new SSD.
+
+
I noted that when I formatted the new SSD, the 128GB drive that was part of the original fusion drive DID NOT show - this is why I did not think it had one. I eventually did pull the logic board out and found the SSD.
+
+
Knowing that Disk Utility didn't see it I assumed it was bad. So I removed it, reassembled the machine, and found the machine works 100%. As for the Bug that @danj thinks might be present, I wasn't able to replicate the issue. So I can't comment on that. I'm thinking maybe the failed blade SSD was causing some issues with the installer??
Recently had to reformat the 3TB HDD in a 2019 27" iMac and reinstall the OS. I made a bootable Sonoma installer USB stick and booted the machine. I formatted the HDD as APFS. When I tried to install Sonoma I got the error: "This volume is not compatible with this update." I found I had to go back and format the HDD as APFS (case sensitive) in order to get it to install. I looked on Apple's requirements site and do not see this documented anywhere. Can someone confirm that this is a requirement or did I just have something funny going on with this machine? Note that the HDD did have an issue where it would no longer boot the machine so the drive may have issues. It formatted and tested normally though.
+
Recently had to reformat the 3TB HDD in a 2019 27" iMac and reinstall the OS. I made a bootable Sonoma installer USB stick and booted the machine.
+
+
I formatted the HDD as APFS. When I tried to install Sonoma I got the error: "This volume is not compatible with this update."
+
+
I found I had to go back and format the HDD as APFS (case sensitive) in order to get it to install. I looked on Apple's requirements site and do not see this documented anywhere.
+
+
Can someone confirm that this is a requirement or did I just have something funny going on with this machine?
+
+
Note that the HDD did have an issue where it would no longer boot the machine so the drive may have issues. It formatted and tested normally though.
Recently had to reformat the 3TB HDD in a 2019 27" iMac and reinstall the OS. I made a bootable Sonoma installer USB stick and booted the machine. I formatted the HDD as APFS. When I tried to install Sonoma I got the error: "This volume is not compatible with this update." I found I had to go back and format the HDD as APFS (case sensitive) in order to get it to install. I looked on Apple's requirements site and do not see this documented anywhere. Can someone confirm that this is a requirement or did I just have something funny going on with this machine? Note that the HDD did have an issue where it would no longer boot the machine so the drive may have issues. It formatted and tested normally though.
[image|3108640]