How to fix could not unmount disk error on mac – causes and fixes
Mac and its features perform great unless there are deleted files or data loss to mess things up. The disk utility on your Mac is a very important and useful system tool that helps to fix specific disk problems. Most of the time its very reliable, but at times it can fail to fix disk problems and even deliver error messages like ‘couldn’t unmounts disk’ error.
Mostly the ‘couldn’t unmounts disk’ error occurs when there’s an improper modification of the boot drive like partitioning, disk verification, during formatting, and others. When this error appears, the disk utility will not only halt suddenly, it will damage data on the disk. The first thing you need to do is start up your Mac using another bootable drive like the OS X recovery or an external drive which is a better option, especially if it’s the one that has issues. The OS X recovery is a partition on the same physical drive so it might not successfully unmounts or modify your internal disk.
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What causes the ‘couldn’t unmounts disk’ error on Mac?
When your Mac displays this kind of error when using the disk utility, it could be because of:
- Interrupted reading or writing operations. Maybe you’re trying to delete a file that you’ve opened so it can’t process a delete before you close the file. Or because your Mac is trying to access data in a hurry which causes a sudden interruption in the system which can lead to data corruption or data loss.
- Presence of malware. If there’s a malicious software running in the background and damaging your Mac, this might cause such an error when you try to do something on your hard drive. This can be due to the software accessing unauthorized websites or making changes to your hard drive without your knowledge.
- Human error.This will happen when you try to delete or format data improperly between ongoing operations and this will cause a disk error.
- Unintentional or forced data formatting. When you delete some of the system data or file accidentally, it can lead to a data loss or getting a faulty disk error.
Other reasons that could prompt such an error include:
- Software or hardware crash
- Corrupted system files
- Improper Kernel installation
- Insufficient permission
- Bad hard drive sectors
Methods to fix ‘couldn’t unmounts disk’ error on your Mac
There are several ways you can fix your disk error.
Use a USB boot drive
If you’re trying to modify your boot drive and this error appears, using a USB boot drive is the easiest method to boot your Mac using another hard drive and running your disk utility from that drive. However, the recovery drive or the installer should be in the drive separate from the primary boot disk with the installed OS on it.
- Attach the USB boot drive to your Mac, then reboot
- While rebooting, hold down the ‘option’ key button, then select the attached boot drive on the menu.
- On the boot menu select the ‘disk utility’ to access it.
- Click on the ‘first aid’ option to verify the disk.
- A second screen will appear that will ask you to select an option. Click on the ‘run’ option to move the process forward.
- Once the repair process is complete, it will show ‘operation successful’ then you can click the ‘done’ option.
- The repair is now done and you can perform the tasks that were halted because of the error.
Use recovery partition
This method will help fix the above error if it’s caused by first aid or when formatting a non-boot partition. You can try and fix the error by booting the recovery partition that is available in all the new version of Mac OS X. This method won’t work if the error was triggered by an attempt to modify the boot disk through formatting or partition.
- Reboot your Mac holding down the ‘option’ key.
- From the boot menu select the ‘recovery partition’ option.
- Click on the ‘disk utility’ on the boot menu.
- Go to first aid to verify and repair the disk or click on ‘erase’ if you want to format the disk.
If the disk throwing the errors is the same as the primary boor partition, this method will not work. You’ll need to boot from a separate USB drive to fix the error.
Use the command line
If you’ve tried the above methods and none has worked, you can fix this error by forcing to unmount the disk using commands.
- From the ‘utilities’ menu access the ‘terminal application’.
- Input ‘disktil list’ on the command prompt to get a list of all the available disks on your Mac.
- Look for the disk you want to force unmount and take note of the drive’s number.
- Once you’ve found the disk, type in ‘sudodisktilunmountDisk force/dev/diskx’
- Then replace ‘dev/diskx’ with the disk number of the drive you want for force unmount.
- Wait for the process to be completed.
Some common Mac error messages and how to fix them
Error |
Fix |
‘Kernel panic, you need to restart your Mac’ |
These are one-off messages that don’t appear frequently. Restart your Mac to clear out the memory and some caches. |
‘Your disk is almost full’ |
Dismiss the error message and save ant opened documents and apps and restart your Mac. Use the get info command to see how much space you have available on your startup drive. Delete some files to make room. Don’t let your free space fall below 10-15% |
Numeric error codes |
Use your search engine to find out what it means by entering the error code exactly as it appears or try the terminal app to decipher the error code. |
Conclusion
Some of these technical issues can be very frustrating at times and can take up a bit of your time and effort to resolve. However, the simple steps mentioned above can help you repair and restore the data on your Mac even if you don’t have any technical skills.
FAQ
What happens if your hard disk fails?
Your computer can freeze occasionally, hear unusual sounds from your drive, data corruption, or detect bad sectors in your drive.
What causes Mac hard drive failure?
Some of the causes for your hard drive to fail includes firmware corruption, human error, power issues, heat, water damage, or mishaps.
