At WWDC 2018 macOS 10.14 or macOS Mojave was disclosed. I am currently on macOS Sierra (10.12) and am looking forward to upgrading to macOS Mojave once its released. I was wondering if it will be possible to update to macOS Mojave without converting to APFS, similar to this trick from OS X Daily on how to upgrade to macOS High Sierra (10.13) without converting to APFS with the command /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO.

  • 4
    Be sure to vote to close for quality reasons and not just because the topic is a beta build. apple.meta.stackexchange.com/questions/2707/… Also realize that people will likely honor NDA so this may sit unanswered (which is fine) or answered with speculation (which isn't fine, but isn't something we can patrol with 100% efficiency but people can vote on) – bmike Jun 4 at 20:39
  • @bmike Thanks! Didn't know there was a ban originally or that the ban was lifted. I guess this is fine question then. Also if people do break the NDA will there answer/comment be removed? – JBis Jun 4 at 20:41
  • Nobody can answer for sure until Mojave is officially released. Even if the feature is (or is not) in some betas Apple can change this anytime. – nohillside Jun 5 at 12:09
  • Wow 2,500+ views with 4 upvotes and 1 upvote for answer (me)? Come on people. If you find helpful please mark the question and the answer helpful. – JBis Jul 2 at 3:28
  • From what I read elsewhere this might need an extension: "Can you run Mojave from HFS+ and properly update it"? – LangLangC Sep 25 at 13:09
up vote 4 down vote accepted

Currently it seems very difficult, but doable to upgrade to Mojave, but not directly.
Currently it seems very, very difficult, but doable to update (in) Mojave.

Similar to avoiding APFS conversion on High Sierra upgrade, only this time you need to go the clone route.

But there are a few catches to this.

Mojave will boot from HFSplus, once installed on it.

The installer will convert the drive where it is being installed on, no matter what. The commandline option to skip conversion is gone. Apple really wants to enforce APFS adoption.

That means you need to install Mojave on a separate volume, which will then be in APFS format. Then you need to reformat your internal main drive that is the real Mojave target as HFSplus. Now clone the external volume to the target.

Reboot into Mojave –– and keep the external drive as a mule.

Since this is currently the real catch:
AppStore app (fromerly Software Update) will currently not work when Mojave is booted from HFSplus. It will launch and update properly when running on APFS.
That means on system updates you need to reboot your APFS mule, update there, then reclone the updated Mojave to your internal work drive (perhaps by inteligently excluding the /Users folder ?).

It is unclear what else might break by this method. It seems to run 'fine' in terms of functionality, and it seems to run even better thanks to HFSplus.
But the procedure is more than cumbersome.

Apple might do two things in the future:

  1. Disable booting from HFSplus completely.
  2. Enable updating while on HFSplus

If you care for the latter, like I do, write to Apple that you want that feature. Fast, Urgently, It's Mandatory.

No

(at least it’s not possible in beta 1)

--converttoapfs isn’t a recognized option in startosinstall.

Image

  • Will mark as accepted when final is released. – JBis Jun 5 at 19:58
  • Interesting that there is the '--eraseinstall' option which notes that it requires APFS... I'm guessing that it is either a mistake, APFS is optional in the GUI workflow or it no longer attempts the upgrade by default. – bjb Jun 20 at 16:50
  • @JBis I guess you can mark this as answer by now. – Marc Oct 8 at 9:53

YES but not an update... (and really not user friendly)

This is actually possible in a weird way, and App Store still works. (managed to install GarageBand, didn't test more complex software)

Here's the following steps that allowed to get a working Mojave on HFS (and clonable with DeployStudio

  1. Get an external harddrive on which you're going to install macOS Mojave
  2. Boot on the drive, finish the install, create an account
  3. Restart, make sure everything is working (right now it will be in APFS)
  4. Plug the external harddrive on a separate machine, and run the Paragon Software APFS to HFS converter (I know it's a third party software, but it's free, and it does the job pretty well)
  5. Boot on the external drive (now in HFS format)
  6. Use any imaging tool that works (DeployStudio for me) and copy the image on the target mac

And voilà ! You now have a working Mojave running on HFS formatted drive. As a bonus, you can even deploy the image with DeployStudio !

That might not be the most easiest way to do achieve it, but it does work. (and doesn't crash, so far ?)

It could be achieved by removing Harddrive/SSD and installing macOS externally with a USB to SATA cable.

  • 2
    is this tested or just theorized? – JBis Aug 1 at 20:44

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