High Sierra install fails - "unable to unmount volume for repair"

Tried the Internet recovery route as well, and no joy.

That said, I am able to force unmount the drive in Terminal - but since the Installer does not appear to try this, it fails each time.
My concern is that my Mini is the repository of my canonical Photos library - and if I am not mistaken, given the pics that my iPhone 8+ is now taking, it would be preferable if the macOS that my Photos library was being stored on, was running HS...

I might be compelled to nuke and pave everything, upgrade to HS – but then face restoring from a Sierra backup in TM – bit nervous that might give me issues...

Hi - this solution still viable?

Trying to upgrade my new SSD drive to High Sierra (currently sitting on Sierra, as it was transferred over from the original HDD start-up drive using Migration Assistant) - but the installer fails when it tries to erase the drive, since it cannot un-mount it.

The 'force' un-mount command in Terminal does the trick, but since the Installer apparently doesn't try this, it fails.

Would your option possibly work still?

I just notice Apple did update the installer again

frist time was on on 5 October

and now on 12 October

did anyone tried new version ?

I see that the installer has been updated:

But - I can't seem to force a re-download. There's no option in the AppStore app.

I have this problem on a 2012 i7 Mac Mini with the Apple drive in it and have the same problem. My MBPr 2013 upgraded without issue.

Same problem for me.

Same on my Mac Pro 2013

I have the same problem on:

Currently Running Sierra Version 10.12.6
IMac (Retina 5K, 27-inch, Late 2014)

4 GHz Intel Core i7

Memory 32 GB

Zeroing out the drive did allow me to install High Sierra as if it was a completely fresh, new drive.

Thanks, but this doesn’t work. First Aid from the recovery drive fails to unmount the drive. BUT First Aid from the boot drive sees no errors.

Tried that...

No joy

😟

I do appreciate your suggestion. Unfortunately, I tried it and it did not resolve the problem.

Did not work for me. I am tired of trying things. I am going to wait for an Apple fix.