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

I suspect it wouldn't let me restore from my Time Machine backup because the backup was made from a different OS --> Sierra. But, that's poppycock, right? Why would it care that I created the backup from a previous OS?!

It doesn't care. You can select to restore files from a previous Time Machine backup of a previous OS. I would choose carefully what you bring over so you can start as clean as possible without bringing in old conflicting files.

How to move your content to a new Mac - Apple Support

How to Clean Install MacOS High Sierra

http://osxdaily.com/2017/10/02/clean-install-macos-high-sierra/

Create a Clone backup

If you don't have a clone backup it's time to start. Just like a seat belt and an air bag protect you in different ways when driving, you need both Time Machine and a clone for full protection. A clone is bootable.

If for some reason you DON'T like the way High Sierra runs, and you want to revert...

1. Boot from the backup clone.

2. Erase the internal drive with High Sierra using Disk Utility and format as HFS+ Mac OS Extended Journaled

3. Clone the backup drive BACK TO the internal drive.

Software used to Clone:

CarbonCopyClonerhttp://www.bombich.com/download.html (All options are available free for 30 days)

SuperDuper!http://www.shirt-pocket.com/ (Free forever to do an erase and install. Purchased version allows for smart updates and schedules)

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

You will need an external drive formatted as GUID and clone software to create the clone. See directions here:

Preparing your backup disk for a backup of macOS | Carbon Copy Cloner | Bombich Software

Software used to Clone:

CarbonCopyClonerhttp://www.bombich.com/download.html (All options are available free for 30 days)

SuperDuper!http://www.shirt-pocket.com/ (Free forever to do an erase and install. Purchased version allows for smart updates and schedules)

SUGGESTIONS FOR EXTERNAL DRIVE

The 3TB or 4TB drive is often the best buy. You can partition large drives to use for multiple purposes.

Check out the Western Digital and Seagate drives. Comes Mac and/or PC. Get the one that is cheapest. Format with Disk Utility to use on the Mac and not use the WD software. Prices vary so check first.

Check the warranty when comparing drives. The longer the warranty the better the drive. Look for a drive with a 2 or 3 yr warranty.

BestBuy, Staples, Office Depot will match Amazon pricing.

Current best buys on Amazon

WD 4TB Black My Passport Portable External Hard Drive - USB 3.0 - WDBYFT0040BBK-WESN

3TB $95.99

4TB $109.99

Comes in colors

http://www.amazon.com/dp/B01LQQH86A/

WD 4TB Elements Portable External Hard Drive - USB 3.0 - WDBU6Y0040BBK-WESN

This drive is smaller and does not need to be plugged in to electrical. Runs off USB

http://www.amazon.com/dp/B017IGERDE/

3TB $88.95

4TB $107.00

WD 4TB My Book Desktop External Hard Drive - USB 3.0 - WDBBGB0040HBK-NESN

http://www.amazon.com/dp/B01LQQHL4E

4TB $97.99

Seagate Backup Plus Slim 2TB Portable External Hard Drive USB 3.0, Black (STDR2000100)

Comes in colors

http://www.amazon.com/dp/B00FRHTSK4

2TB $68.80

4TB $106.99

Seagate Expansion 2TB Portable External Hard Drive USB 3.0 (STEA2000400)

http://www.amazon.com/dp/B017KE8OG0

2TB $69.99

4TB $109.99

Don't get a WD My Cloud drive. Does not work well with clone and Time Machine.

USB 3.0 drives work on USB 2.0 but you do get 2.0 speed. They are cheaper because they are popular PC drives. If you get a new computer you'll get the bump to 3.0 speed. I don’t recommend FW. The newer computers don’t have FW ports. You would need a connector in order to use the drive on a newer computer.

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

So, did the same thing. Loaded from backup external drive... it failed also. Chatting with Apple Support, they told me to me to either 1) do a full reinstall from a clean disk or 2) wait for a software update to fix the problem. They know there is a software (i.e. not a hardware) problem.

Tks Bill

@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?

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.

If your Mac won't boot, there's something else wrong and I can't guarantee the following command will fix your issue. However, with that said, the commands can be executed from recovery mode as well. If your machine's already hosed, I supposed it's worth a try, but I doubt this will fix your problem:

I just remembered after posting, the command may need to be further tweaked for the Recovery Partition. I can check sometime tomorrow on my home machine for you. In the meantime, could anyone else chime in if the below works in the Recovery Partition?

1. Boot into the Recovery partition and click the "Utilities > Terminal" menu item to launch Terminal
2. In the Terminal window, copy paste this command exactly and press the "return" key:

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

3. We're going to do the same thing again, only this time with a different command. Remember to press the "return" key after pasting it in:

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

If after trying this you are still unable to boot, you're going to unfortunately need to reinstall macOS Sierra from the Recovery Partition or from Internet Recovery (this will NOT overwrite your personal data, it will only write over system-level files). Once you can boot normally again you try again by following these steps exactly. Good luck!

It's possible your drive is bad.

• Make a clone backup of your drive.
• Boot from the clone drive.
• Open Disk Utility and select your internal Macintosh HD and erase.
• Run First Aid.

• Install either Sierra or High Sierra on our internal drive. (If you do not have an SSD drive, I suggest you stick with Sierra to install.)
• Bring back your data from clone. I suggest a manual move of data so you don't bring back corrupt files.

Download Sierra

https://support.apple.com/en-us/HT208202

Have you removed all external drives then restart?

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.

As I mentioned this could be a sympton that your drive is failing. Have you considered doing the install on an external drive? This would allow you to recover any data off your internal drive as well before erasing.

I had no luck either but had backups so once I did internet recovery I was able to wipe the drive and I just put normal Sierra back on and gave up on high Sierra. So if you got backups and your fine with Sierra I would say internet recovery (Command (⌘) – Option (⌥) – R ) then you should be able to wipe the drive and go from there.

Ditto on my 2015 Macbook Pro. Created a USB stick with High Sierra, booted off that, ran Diskutil against the SSD on the laptop, no errors reported, but can't unmount the disk there too. Entered the terminal, did a diskutil unmount /dev/disk21, failed with a UID=0 voted no (or something like that) error and didn't unmount the disk.

Next I tried a diskkutil unmount force /dev/diskk21 command, that got the device unmounted. Ran disktuiil volumerepair on it now, no errors.

Rebooted back to the ssd, tried the install again. Same error. ARGHH.

Next step is to take a fresh time machine backup, wipe the disk, install High Sierra on it, then restore from the backup. What a PITA.

Same problem here.

Tried updating by booting from install stick ... no joy

Took it into Apple - after some diagnostics they determined that there was no problem with the actual drive, but after a few different "levels" of diagnositcs - they finally determined that it was a "software error" (not hardware).

At this point the apple guy was quick to say the only way to fix it - was wipe the drive and go from there, and warned me that if I did a restore from Time Machine - the problem would come back.

Ironically - he wiped the drive after I acknowledged his advice, thinking I gave him consent (he knew I had a fresh backup). When I realized what was going on - I felt sorry for the dude... I had just packed up that morning via Time Machine so I let it slide and restored when I got home.

So I am in the same boat here - unable to update to High Sierra as I am not willing to wipe my drive clean.