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Unable to unmount disk. High Sierra Install

Drich290195

Drich290195

macrumors 6502
Original poster
Apr 2, 2011
467
6
I’m trying to install on a Mac mini 2014 that I have installed a SSD in. It begins to install shut down and restart. At the point it should be converting to the new file format it restarts and says unable to unmount disk for repair and fails the install. (Or words to that effect)

The disk is fine and checks out fine in first aid.

No issues booting back into Sierra. Any ideas?

Thanks
 
I also tried updating my Mac Mini late 2014 to High Sierra and ran into the same issue, so I am interested if there are others. Mine is pretty much standard, with standard 1 TB HDD (not SSD). I also tried unmounting the Macintosh HD manually, but it won't let me do that either. Tried rebooting with Command+R, and running disk utilities, but no cigar...
 
Can't speak for the OP, but in my case the first aid step of that post already fails as it needs to unmount the volume in order to do the repair.
 
The more I read the more it seems common to a particular generations of machines.
 
loek said:
My Mac Mini is stock with a 1 TB internal hard drive, not solid state.
Click to expand...
Let me know if you get any joy solving it. Good to know it’s happening to stock seven though that does not really help
 
So far no joy. It all boils down to the fact that the internal hard drive volume cannot be unmounted. Once I can figure out a way to fix that, I assume the installation of High Sierra will work OK. However, I have not yet found the magic spell to convince macOS that the drive is truly not in use and can be released. I may have to take it in to an Apple store and have someone more knowledgeable take a look at it.
 
loek said:
So far no joy. It all boils down to the fact that the internal hard drive volume cannot be unmounted. Once I can figure out a way to fix that, I assume the installation of High Sierra will work OK. However, I have not yet found the magic spell to convince macOS that the drive is truly not in use and can be released. I may have to take it in to an Apple store and have someone more knowledgeable take a look at it.
Click to expand...

While not the ideal solution would wiping the drive and starting a fresh solve the issue by formatting the drive to APFS from a usb installer then installing. Then restore from time machine.
 
Yeah, that is likely what I'll need to do. For now I'll stay on 10.12.6 until I find a good time to do this.
 
FWIW, sitting with the exact same issue. Running a 2012 1TB HDD Server edition Mac Mini, all stock.

Currently on Sierra, cannot make the jump to HS.
 
My suggestion is pretty much like a broken record:

If you're having trouble installing, try creating a bootable USB flashdrive version of the installer.
Then... boot from the flashdrive and try the install that way.

I highly recommend the free little app "Boot Buddy" to create the installer:
Boot Buddy – sqwarq

I suggest a flashdrive 16gb in size. You can -try- 8gb if that's all you have.

Then ...
- Boot from the flashdrive installer
- Open Disk Utility and NUKE the internal drive -- Erase it back to HFS+ with journaling enabled.
- Open the installer and do the install...
 
I managed to get High Sierra installed after running the following command which released the lock on the volume:
sudo mv /.quota.ops.user /.quota.ops.user.org
sudo mv /.quota.user /.quota.user.orig

High Sierra is now installed. The subsequent upgrade of macOS server made me less happy, but that is a story for another thread.
 
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