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Question: Trying to erase disk in Disk Utility to trade in unit; keep getting "Unmounting disk - couldn't open device" and cannot erase. Help!

I am trying to erase the disk in my MacBook Pro (to trade it in)- using Disk Utility and keep getting "Unmounting disk - couldn't open device" - so cannot erase. Help please.



MacBook Pro 15", 10.14

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Feb 14, 2019 11:42 AM in response to leroydouglas In response to leroydouglas

In Disk Utility it appears the only thing I can erase is the "Parent" drive (in my case "Apple HDD Toshiba ....." when I click on Erase I am prompted to enter a "name" . the "format" and "scheme" are already listed - name, however, is a blue "untitled". If I leave it as untitled operation fails due to "unmounting disk, couldn't open device" - If I enter the name as Apple HDD ..." I get the same result.

Feb 14, 2019 11:42 AM

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Feb 14, 2019 11:53 AM in response to wallyb444 In response to wallyb444

Hi, wallyb444 !


Sometimes when Disk Utility gets stuck like this for me, I choose a PC format to initialize the HDD then reformat with the Mac settings. So after you give it a name, click the first pull-down menu and select MS-DOS (FAT), then click the second pull-down menu and select Master Boot Record. Go ahead with the reformat. When it completes, just re-format again with the Mac settings.


If this doesn't work for you, it's quite possible there is a hardware issue with the HDD.


Good luck !

Feb 14, 2019 11:53 AM

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Question: Trying to erase disk in Disk Utility to trade in unit; keep getting "Unmounting disk - couldn't open device" and cannot erase. Help!