Fix: High Sierra Install Fails-"Unable to Unmount Volume for Repair"


When I tried to install High Sierra on my Mac, it says “unable to unmount volume for repair” and asks me to restart and back to normal login. I found no other ways to install High Sierra.
Here you can find the real fix.

Fix 1: Submit the following commands

Open the Terminal App in Utilities or Application. Type the following commands.
sudo mv /.quota.ops.user /.quota.ops.user.org
mv /.quota.user /.quota.user.orig
Press the enter key to submit the command.
Fix 2: Internet Recovery mode or USB drive

  • Boot to internet recovery or a USB drive with the High Sierra Installer
  • Open Disk Utility and mount the Mac volume and close Disk Utility
  • Go to the command line terminal

diskutil umount force /Volumes/Macintosh HD/

  • Run diskutil apfs convert /dev/disk1s1

Finally, reboot your Mac and High Sierra can be installed from internet recovery mode or USB drive.
I hope the above-mentioned solutions will be helpful to install High Sierra and fixes the problem “unable to unmount volume for repair”. If you have any suggestion over this article or if you have any solution, let us know via comments.

10:03 am

One response to Fix: High Sierra Install Fails-"Unable to Unmount Volume for Repair"

Leave a Reply