Install High Sierra before Mojave?

[wdegillio]

I'm currently running Sierra on my Mac Mini with no problems. I'm considering updating to Mojave in the near future. Is it best to install High Sierra first before upgrading to Mojave, or can I go directly to Mojave from Sierra? Some of the posts I've seen recommend upgrading to High Sierra first, but those posts seem to involve older Macs that require specific firmware. By the way, I have 2 SSD's installed in my Mini; a Samsung 500 GB as my boot drive and an OCZ 500 GB for samples. Thanks in advance for your help.

[HCMarkus]

Hopefully, someone in the know will weigh in here.

I just did a quick search over at MacRumors.com and couldn't find anything on point. I did note a few comments from people for whom Mojave caused serious grief. As such, the traditional advice is pertinent: Back Everything Up Before Installing Mojave!

[mikehalloran]

The word is that High Sierra installs a firmware update required before a Mojave install. Not sure I'm buying into this as the Mojave installer runs its own firmware update. Unlike earlier updates, the 10.14 screen goes grey for awhile and it takes a few minutes.

I installed onto my unsupported iMac using the hack from a USB flash drive. Unlike previous USB installers, it needs to be 16G or more.

Yes, a few builds of 10.13 update the firmware on install as does 10.14 but if you need to revert to an earlier build or OS, this is not a problem. Even though one of my drives boots into Mojave and another High Sierra, I can still Option Boot into El Capitan. None of the firmware updates prevent this.


The reason I recommend updating from High Sierra is if there's the possibility that you want to go back to OS 10.13. APFS Snapshots lets you do it in a few minutes instead of a complete Time Machine restore.

viewtopic.php?f=4&t=64689

You can't use Snapshots to revert back to Sierra. For that, you need to do a Time Machine Restore.

[HCMarkus]

The word is that High Sierra installs a firmware update required before a Mojave install. Not sure I'm buying into this as the Mojave installer runs its own firmware update.

This is definitely true for Mac Pro 5,1s. HS 13.6 update using a Mac EFI GPU is a necessary condition precedent for Mojave installation. Then Mojave updates firmware again.

Not sure about Mac Minis, as is the question here.

[mikehalloran]

The word is that High Sierra installs a firmware update required before a Mojave install. ...

This is definitely true for Mac Pro 5,1s. HS 13.6 update using a Mac EFI GPU is a necessary condition precedent for Mojave installation. Then Mojave updates firmware again.

Not sure about Mac Minis, as is the question here.

Me neither. The Mini, like the iMac, must be a 2012 model or later to be Mojave compatible.

You can make a Mojave install drive and download the 10.14 installer following the instructions on this page. If installing on a supported Mac, no need to follow the additional instructions after the install.

http://dosdude1.com/mojave/