MP 1,1-5,1 [SOLVED] Mojave won't install on SSD. "You may not install to this volume because the computer is missing a firmware partition."

[minifridge1138]

Hello everyone,

Just in case anyone runs into this error, I wanted to document it.

I have a 4,1 -> 5,1 Mac Pro with an RX 580 and I wanted a fresh install of Mojave on a new SSD. I had been running Mojave for a couple of years and was already running the latest firmware. So this is just a simple OS install.

I followed the usual instructions to create a Mojave Bootable USB Installer. Inserted the USB drive in one of the front USB slots and turned the Mac on. After ~10 minutes all I had was a blank screen, so I pushed the power button to turn it off and suddenly that woke the computer up and I was at the install menu.

I formatted the drive as Mac OS Extended Journaled and then tried to install Mojave on the newly formatted drive. But the SSD was greyed out with this error message:
"You may not install to this volume because the computer is missing a firmware partition."

I wasn't expecting that. After a bit of searching, I couldn't find a definitive answer but decided to reformat the drive as APFS. Luckily, that solved the problem.

Good luck to anyone that runs into this in the future!

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[Macschrauber]

Typical misleading error message from mothership.

Why couldnt write they that it needs APFS?

 

[haralds]

That's new. It used to install on HFS+. Only upgrades automatically converted.

 

[Don_Con]

Thanks for this post. I am on a 5,1 cMP running 10.13.6 myself, and I just did my GPU/Boot Room upgrade to 144* to prep for a Mojave install.

All my drives are current HFS+, but in the other Bootrom thread it was mentioned Mojave wouldn't care if my destination drive was still HFS+.

Worst case scenario is I can try ands ee what happens.