Error when trying to install High Sierra on iMac19,1

[psygoat]

Maybe iMac19,1 is too new for High Sierra. It boots the installer ok, but when it prompts for a destination disk for the install, all disks are greyed out and this error message is shown when clicking one:

The version of macOS installed on this Mac is newer than the version you are trying to install. When a new update is available, you can install it from the updates pane in the Mac App Store. If you want to reinstall macOS, please use macOS Recovery.

This is not entirely unexpected, but what *is* unexpected is the persistence of that message after removing any other SSDs with a copy of macOS already installed. It will still show that message with only a freshly erased SSD plugged in (and the USB installer disk). I tried erasing the destination disk as both HFS+ and APFS. I created the installer disk using gibMacOS.
I have never encountered this error message in years of doing this (including High Sierra on my previous build). Does anyone have an idea what might cause it?

 

[Cosmix]

Maybe iMac19,1 is too new for High Sierra. It boots the installer ok, but when it prompts for a destination disk for the install, all disks are greyed out and this error message is shown when clicking one:

This is not entirely unexpected, but what *is* unexpected is the persistence of that message after removing any other SSDs with a copy of macOS already installed. It will still show that message with only a freshly erased SSD plugged in (and the USB installer disk). I tried erasing the destination disk as both HFS+ and APFS. I created the installer disk using gibMacOS.
I have never encountered this error message in years of doing this (including High Sierra on my previous build). Does anyone have an idea what might cause it?

Hi,
SMBIOS iMac19,1 is too new for High Sierra. You may try SMBIOS 18,x ( where x = 1, 2, 3).

Also, using "older" HW (e.g Kaby Lake) could help running High Sierra.

In your case, may be a spoofed CPU could help.

If choosing SMBIOS iMac19,1 , you may use Mojave ... Sequoia.

Cheers

 

[Jamesbond007]

Maybe iMac19,1 is too new for High Sierra. It boots the installer ok, but when it prompts for a destination disk for the install, all disks are greyed out and this error message is shown when clicking one:

This is not entirely unexpected, but what *is* unexpected is the persistence of that message after removing any other SSDs with a copy of macOS already installed. It will still show that message with only a freshly erased SSD plugged in (and the USB installer disk). I tried erasing the destination disk as both HFS+ and APFS. I created the installer disk using gibMacOS.
I have never encountered this error message in years of doing this (including High Sierra on my previous build). Does anyone have an idea what might cause it?

I still run MacOS Sierra 10.12.6 and High Sierra 10.13.6 on my main Z390 system. So it is certainly possible to run High Sierra on an Intel 9th generation CPU and a Z390 motherboard.

But as pointed out iMac19,1 is too new for High Sierra. I use iMacPro1,1 (I use a CPU without integrated graphics so I use the iMacPro SMBIOS) for High Sierra / Mojave / Catalina / Monterey / Ventura on my system.

You can try iMac18,3 as suggested. However, please note that High Sierra does NOT support the iGPU in the 9th generation CPUs. You should run Mojave or later if you need to use the iGPU.

 

[psygoat]

Thanks for the replies guys, it makes sense that iMac19,1 is too new. I just got thrown off by the error message. Interestingly, I figured out that I can boot from an existing High Sierra install (which was my original goal) as long as the MinVersion and MinDate fields for the APFS driver in OpenCore are set to -1. I may experiment with this more, but it sounds like it might not run stably unless I change the SMBIOS. I have used the iMacPro1,1 on this system before but I switched to iMac19,1 to use the iGPU headless.
I am also curious if other people have experience dual booting older and newer macOS versions together. I previously had a dual boot setup with Mojave and whatever the latest version was (Big Sur through Sonoma) in the same APFS container but I ended up having issues with "underallocation" in the filesystem. Maybe a topic for another thread.

 

[Jamesbond007]

I am also curious if other people have experience dual booting older and newer macOS versions together. I previously had a dual boot setup with Mojave and whatever the latest version was (Big Sur through Sonoma) in the same APFS container but I ended up having issues with "underallocation" in the filesystem. Maybe a topic for another thread.

I run Mojave / Catalina on one NVMe SSD and Monterey / Ventura on another NVMe SSD on my system (A third SATA SSD hosts Sierra / High Sierra.). They are all on separate APFS containers. Apart from some error message on High Sierra / Mojave (related to APFS versions on the newer systems) I have no problems. After I boot the older systems I unmount the partitions for the newer systems from the finder manually.