Then this: diskutil erasedisk is the ID of your disk.Type this very carefully (sudo might not be necessary): sudo diskutil unmountDisk force /dev/disk2 When your computer finishes starting up, choose Disk Utility from the Utilities window, or from the Installer menu if youre started from an installation disc.(note: be EXTREMELY careful, ask you could wipe your computer if you do this wrong) Thankfully I ended up fixing it quickly (with a little googling). I was getting things like: ”could not modify partition map” and “couldn’t unmount disk.” Other things could be things like “couldn’t open device.” Erasing an External USB or Hard Drive that keeps failing in Disk Utility Check if the USB stick is encrypted or has no file system Update the USB driver Repair corrupted USB drive on Mac with Disk Utility First Aid Repair. You get this error, and the details vary depending on the format type you try That might be because the disk is a Windows/Linux bootable formatted as FAT-32, which OSX cannot read.Īnd then when you try to erase in disk utility, the USB is greyed out and First Aid doesn’t work, you can’t repair it, and you can’t mount or unmount it. In its place would be 'disk0s2.' It is this indented entry that you want to erase.Are you trying to erase a USB drive on your mac but getting this error as soon as you insert it? You might see that it is displayed on the list as: To be sure you do this right, please observe that the drive may appear in the list as ghosted because it is unmounted. Use the device reference in this next command. It will appear similar but not the same as this: /dev/disk0s2. In the output, you should find your Fusion drive listed. At the prompt paste these lines individually pressing RETURN at the end of each line. If that doesn't work then quit Disk Utility and open Terminal from the Utilities' menu. Look for the disk that you want to force unmount and take note of.

In the Terminal window, type in the following command: diskutil list This will list down all the available disks on your Mac. After doing that click on the Unmount button in the toolbar to see if the disk disappears from the Desktop. Normally, any Couldnt Unmount Disk error is attributed to circumstances where the boot drive is being modified or is being used by an application or. To do this, follow the steps below: Launch Terminal by navigating to Finder > Go > Applications > Utilities. Try repairing the disk in Disk Utility using First Aid.

Could not unmount disk macbook air