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

When booted in recovery mode, I am able to force unmount the disk.

I don't wish to REFORMAT and lose everything. Even though I do have multiple backups (TimeMachine and Carbon Copy Cloner [aka CCC]), I don't want to have to go through everything (including licensed apps) to make sure everything is correctly restored and all the licensed app are working correctly after the install (assuming that actually works).

I've tried the unmount followed by running the APFS conversion command - that's where it also fails (see earlier posts).

> using disk utility, got disk error, tried again, then it worked

I get that frequently. I think you can safely ignore it. If you want you can likely find the full guide for the software (or even the source code "the real guide" and see what the error code is), however you'll likely find what you already know: it gives and error code the first time but not the second 🙂 Perhaps avoidable by doing steps in some order: but easy is as easy does.

@dianeoforegon

So, unlike many others, I bit the bullet and decided to format my drive and start from scratch. macOS High installed fine. Previous to this, I ensured I had a recent Time Machine backup on an Airport Time Capsule. Additionally, I created another Time Machine backup on a locally attached USB drive that was formatted Mac OS Journaled, Case-sensitive. When I used Migration Assistant to restore from Time Machine, it wouldn't let me use the locally attached drive because it said that it wasn't Case-sensitive, like the main drive. I double-check this and IT IS set to Case-sensitive. So, I tried restoring from the Airport Time Capsule and it just hangs saying "Loading Backup." I don't this is a case of me being impatient because I let it run for 2 days and it kept saying the same thing.

Any ideas?

@dianeoforegon

I've heard that suggestion about also having a clone and plan on incorporating that into my backup strategy. However, I'm confused as how this will help me upgrade to macOS High Sierra. Won't restoring from a clone simply bring me back to my macOS Sierra installation? Also, does simply dragging the files from the Backups.backupdb folder restore all of the OS specific settings? I'm trying to upgrade from macOS Sierra Server to macOS High Sierra Server. There are some critical databases the need to be installed and I'm not sure just dragging them over will work. I'm upgrading my server based on an Apple Knowledge Article I read on the subject.

Joe

A clone is part of a good backup strategy. It's bootable where Time Machine is not. It's a bit easier to manually drag over files if needed. If you have a clone, you can select to import from the clone rather than select migration from Time Machine when setting up a new Identity. I mentioned so you can incorporate in the future for your backup strategy.

However being specific to upgrading to High Sierra....Since you have problems with restoring from Time Machine due to the case-sensitive issue, it appears you will need to manually do a clean install. Restoring to a server is also a different scenario and should have been mentioned for users to know what to suggest. I have no experience with setting up a server. It might be beneficial to start a new post with specifics to your issue and with full details. Users with the specific knowledge to help with setup of server will be best able to advise you.

i too have had this issue since 10.13 was first released. MacMini 2012.

I discovered my SSD (stock Apple) was failing First Aid with a unable to unmount message when booting on an external drive or in recovery.

The only way i found to fix that issue was to clone the SSD boot drive, hard force unmount the SSD (terminal: sudo diskutils unmountDisk force /Volumes/Macintosh\ HD), erase the SSD volume in Disk Utils, and finally clone back the original drive to the SSD. Rebooting in recovery and running First Aid confirmed that volume would unmount and pass.

Unfortunately attempting to install High Sierra resuls in the same unable to unmount error.

Additionally, rebooting in recovery, the SSD Macintosh HD again fails First Aid with an unable to unmount message. in my case (others?), the installer is not just failing, but leaving the SSD in a corrupt state requiring erasing the drive to fix.

it seems the only successes I've read are new installs - format, install, restore from a pre-install drive copy or Time Machine backup.

Wow - I spent an entire day messing around and even swapped out the HDD for an SSD in my Mac Mini Late 2012 - those two commands should be run before running the installer from your live OS X installation.

Having just done that and rebooted, now getting the "Installing: 41 Minutes Remaining" screen....

I thought this could not possibly work, but had some time to give it a try - renamed those files and 30-45 minutes later my MacMini was running High Sierra.

Why 2 months after 10.13s release has Apple not addressed this in the installer.

Thanks for sharing this Andy, ends 2 months of frustration.

This worked for me as well. However, at one point the second mv command did not find the original file. I tried to install anyway. Big mistake. It stalled and I had to reinstall from time machine. This time both mv commands were successful and the install went through without a hitch.

Thank you very much!

Since my install was already in a state where I was unable to boot to my original macOS partition I had to ressort to terminal from the installation media (recovery should do as well). From there, the commands are:

cd /Volume/Macintosh \HD (or whatever the name is - use df to find out)

mv .quota.ops.user .quota.ops.user.orig

mv .quota.user .quota.user.orig

This fixed it for me.

Awesome after so many reboots and failed attempts at getting the system volume to unmount etc, it beggars belief that Apple haven't published this specifically or indeed included it as part of the update...its almost as bad as Microsoft!

I've been an IT systems engineer for over 25 years and it took me until 2011 to turn to Apple as my personal preference and something as simple as this, is likely to put off those less IT literate. Get on it Apple before your reputation suffers.

Thanks Andy

Thank you for the post, I have been searching everywhere to find help with this. Really stupid question, so sorry, but I am not super computer literate... would you mind explaining where/how I input that code to fix the unmount volume issue?

Open the Terminal.app in Applications/Utilities.

Copy/paste the commands

sudo mv /.quota.ops.user /.quota.ops.user.org

Press the Enter key to submit the command

mv /.quota.user /.quota.user.orig

Press the Enter key to submit the command

Thank you very much, andy260!

This solved it for me, too.

(iMac 5K 2015 with 3TB Fusion Drive)

I just called back Apple Care to tell them about this solution, since the second level support wasn't able to solve this back in September 2017.

Wish I could report that the solution offered here, worked for me!

2012 Mac Mini 1TB HDD running macOS Sierra. Never had any issues before, until now.

Booting from USB-installer, sees the same issue.

Hoping someone has further suggestions...