Mac os could not unmount disk how to#
Mac os could not unmount disk mac os x#

Restart the Mac by holding the “Option” key and choose the recovery partition.This will not work if the error was caused by trying to change the startup disk through partitions or formatting, and you will have to use the above method with a startup disk instead. If the Unable to Unmount error is caused by first aid or formatting a no-boot partition, you may be able to fix the error by booting from the recovery partition that comes with all new versions of Mac OS X.

Mac os could not unmount disk how to#

How to Fix Disk Utility errors via Mac Recovery Partition For older Macs with earlier versions of Mac OS X, anything with OS X 10.6 or earlier usually has a SuperDrive and therefore comes with a bootable DVD that can serve the same purpose. Such boot discs are easy to make yourself, here are instructions on how to create boot discs for OS X 10.9, OS X 10.8 and OS X 10.7.

Mac os could not unmount disk mac os x#

This is a great example of why it is very valuable to have a bootable USB stick up whatever version of Mac OS X is running on your Macs, as without a separate startup disk, some of these errors would be unsolvable. You will need a Mac OS X startup disk to complete this task, I used a Mavericks boot installation drive for this, but others should work too, be it installation drives or just recovery discs, most importantly they are bootable and stand alone Of the primary boot disk where the installed operating system is stored: This is the recommended method as the error should always be fixed. How to Fix the disconnect error with a USB boot drive We will also show you a way to force unmount a drive through the command line, although that approach should be used with caution as it can lead to data loss on the affected drive. We’ll cover both with a little explanation. This allows you to fix the problem regardless of the cause in two ways – the first is a fix to fix the problem while the other just works sometimes.

For the startup disk, it shouldn’t matter what version of Mac OS X it is for (assuming at least 10.7, 10.8, 10.9, 10.10, 10.12, 10.13, 10.14, etc.), the only requirement is that it has Disk Utility – that they all do it.

For the first situation where the boot disk is changed, the easiest solution is to boot from another disk and run Disk Utility from there. Usually the error message “Unable to Unmount Disk” appears up if the current boot disk is changed, or if a disk attempted to be erased, the erase may have failed with a disk error that could not be removed.