IMac – How to install OSX on NVMe drive only (no SATA drive)

imacssdusb

I just pulled the 128GB NVMe SSD + 1TB disk drive (known together as a fusion drive) out of a late 2014 27" iMac. I put a new, blank WD Blue 1TB NVMe drive in (alone) but have been unable to install OSX so far.

The default OSX for this model was Yosemite. However, it seems Yosemite cannot see the NVMe module. I created a bootable Mojave USB which can see the drive (and was able to format it), but when I tried to actually install the OS from the bootable USB I got the "installer is corrupted"

(Note: This mac has run every version from Yosemite up to Big Sur which I removed)

How can I install OSX on a blank NVMe SSD for a late 2014 iMac?

Best Answer

Apparently the downloads you get get off apples website use certificates that have expired. In order to work around this you have to download a "full" OSX install.

I re-downloaded an installer for Mojave using the following command on another mac

softwareupdate --fetch-full-installer --full-installer-version 10.14.6

Then created a bootable USB drive from this and was able to install successfully