I'm getting an error message trying to use a new external hard drive-"couldn't unmount disk". How do I fix that?

In Disk Utilities and with the External Drive attached - the drive should appear in Disk Utilities - Does it ?

In DU click View >> View All Attached Devices >> Choose the Upper Most Drive by the Manufactures Name ( not the volumes indented and list below ). That is the Drive to Format as per ones need ( APFS / GUID ) or HFS Journaled / GUID or some other format if moving drive between Apple and Windows computers.

Hello,

Error 69888…

sudo fuser -c /dev/disk2s2

macos - Error: -69888: Couldn't unmount disk - Ask Different (stackexchange.com)

https://discussions.apple.com/thread/253542002?answerId=256630010022#256630010022

I am having a similar issue. I want to copy across my photos library to an external hard drive but am unable to do so because the external drive is in NFTS. I have followed the advice above, however:

1. I select the external hard drive
2. I click erase and chose ExFat
3. I receive the message, "Unmounting disk - the volume "Toshiba Ext" on disk4s1 couldn't be unmounted because it is in use by process 0 (kernel). Couldn't unmount disk: (-69888). Operation failed..."

I looked at videos on YouTube which then discuss coding fixes. That is beyond my skillset.

How can I proceed simply?

Thanks in advance.

I have the same WD MyPassport 2TB EHD and as of either today or yesterday it is not showing up on my screen when I connect it to my new MacBook Pro. I was told to go on disc utilities and was not able to mount. I tried fIrst aid but that didn't work either. There was a software update last night that didn't complete last night (not sure why) so I updated it this evening. Not sure if the update has any bearing on why my EHD suddenly decided not to work. Any idea what I need to do? I am a new Mac user and not technically savvy. Any help would be appreciated. Thanks!

I had this same issue yesterday with a WD MyPassport 2TB SSD. I found that I had to open disk utility, then force eject the external drive before being able to erase and reformat it in disk utility. I kept receiving an error in DU that it wasn't able to unmount the drive, one error mentioned the drive was in use (I'm guessing by the WD utilities in the background). I tried to eject it and received an error that the drive was in use and not able to eject, so I had to force eject it. After that, I was able to erase and format it in DU. Now it is operating as expected (I'm using this mainly for Time Machine backups).

May I suggest strongly to uninstalled the Bundled Software at probably came when the WD Drive was new. The bundles software often time introduces a conflict with the macOS installed on the computer. Plus, more often than not - their software is buggy as least of incompatible at best.

Besides, macOS is very very capable in managing the External Drive without third party software complicating matter

Thank you for taking the time to reply. Unfortunately, I have no idea what I need to do. Could I trouble you please to unpack this for me? If it's too much trouble, then no worries. I really know nothing about Mac.

Thanks for that. I have looked at spotlight and system preferences and the external hard drive does not show up in privacy.

I think the answer is in the previous reply you sent me but unfortunately I don't know enough to follow your direction there.

I had another go and followed your advice to JoFerrand on the other post. I entered the command in the Terminal.

Last login: Sun Jan 16 10:33:30 on console

bernieedmond@Bernies-iMac ~ % ^[[200~sudo fuser -c /dev/disk2s2~

zsh: bad pattern: ^[[200~sudo

bernieedmond@Bernies-iMac ~ % 

bernieedmond@Bernies-iMac ~ % ^[[200~sudo fuser -c /dev/disk2s2~

zsh: bad pattern: ^[[200~sudo

bernieedmond@Bernies-iMac ~ % sudo fuser -c /dev/disk2s2

Password:

Sorry, try again.

Password:

/dev/disk2s2: 

bernieedmond@Bernies-iMac ~ % sudo fuser -c /dev/disk2s2

/dev/disk2s2: 

bernieedmond@Bernies-iMac ~ % 

I then went back into DiskUtility and tried to erase the external hard drive and got the same error message:

Unmounting disk

The volume "Toshiba Ext" on disk6s1 couldn't be unmounted because it is in use by process 0 (kernel)

Couldn't unmount disk. : (-69888)

Operation failed...

Final question, then I will give up... am I doing something really basic incorrectly?

Thanks for your patience.

Thank you for taking the time to add your comment. By force ejecting the hard drive and retrying to format worked for me.

It could be Spotlight trying to index it, exclude it inSys Prefs>Spotlight>Privacy

You want to add it in Privacy.

Just tried to connect a second G-Raid 20 gig for back up and the brand new 24 inck M1 iMac says: "Cannot connect accessory".

Tried 10 times. So what do you think is wrong here.? the HD or the iMac?