Mojave

Hi, does your MacMini 2014 have an SSD drive, i'm wondering if that's the issue here... i ran the installer on a Mac Mini 2012 with HDD and it ran fine... on my MacBook Pro (see above), that has an SSD, i got the error... i made a fresh Time Machine backup, created bootable Mojave installer flash drive, booted from the flash drive, reformatted my MBP drive (used APFS format, was Apple Extended, Journaled), ran the installer from the flash drive and restored from TM backup when prompted... and hey-presto i'm typing this now from my MBP running Mojave.

I see many others also with Mini "Late 2014" and a spinning disk. While it may not be an ideal solution, the solution shown does work and is what the escalated support person confidently suggested to me.

1. I created a boot disk for Mojave on a USB stick.
2. Booted to that (holding down Option upon reboot)
3. Erased the disk
4. Installed Mojave without issue this time.

You still could try the TM backup, bootable installer, reformat, install, TM restore route?

In the upper left hand corner of the Disk Utility window, click

the icon and select "Show all devices". Then select the drive

itself and then run First Aid on it and see if that helps.

I have the same issue. Tried suggestion here, and still the same. All checks out fine, but still can't install with the same error.

HOWEVER, interesting that the OP and I both have the same model Mac Mini - Late 2014 (mine with SATA disk).

Hi, yes this is my next plan., backup (TimeMachine etc.) - create bootable installation media, boot to installer, select and reformat drive and install 'fresh' macOS, then migrate settings etc. from TimeMachine backup. But... would be nice to know why this isn't working as an in-place update?

I also have a Mac Mini "Late 2014" model and it is giving the exact same error. Error appears right after the installer asks you to log in after selecting the disk to install to. The login prompt says it is trying to "add a new helper tool". Not sure why the current answer is marked as the answer, as I found it completely not helpful at all - this is an in-place upgrade - no old or new disk.

I agree that I can always do a clean install. This is always an option, but this install is supposed to work without having to do a clean install. Beyond it not working, my further complaint is that the error that is given by the installer is not correct or useful. It says that you need to run First Aid, but First Aid comes back with flying colors.

100% agree with you, and this was the confident solution delivered by Apple Chat; however, yes it doesn't seem to address what the real problem is. Further to your point, error notification perhaps is incorrect.

Hi there, have you j=had a reply from Apple, or managed to sort out the issue and installed mojave?

I have an iMac, 2014, and getting the same error, have run disk repair, and got a confirmation upon completion that the repair was successful - yet when i try to install Mojave the error message returns....**** annoying.!!

No. No reply at all. Apple Support have been as silent as a grave. I presume that they know that there is this problem but either they don't care or they don't know how to solve it. The good old days of Steve Jobs have gone forever, sadly. Apple is no better than Microsoft now, only far more expensive and glitzy.

Same issue, Mid 2012 13-inch MacBook Pro running macOS High Sierra 10.13.6 with 16GB RAM & 500GB SSD.

My Mini has a spinning disk, so might just be specific Mac Minis with the issue.

The same thing is happening on my iMac late 2015 with SATA disk. Why isn't there any solution from Apple yet? Are those guys asleep?