MacBook Pro: Time Machine drive fails to eject

zim528 wrote:

I have an external hard drive attached by cable to my MacBook Pro, which I use for Time Machine backups. Problem is if I want to unplug the hard drive (when I need to go somewhere with the computer). I’ve done this successfully for years, simply by clicking on the Eject button in a Finder window. If a backup were not underway the disk would eject almost immediately, and if a backup were underway I’d get a message asking if I wanted to stop the backup, I’d say yes, and the disk would then eject.

But now when I click the Eject button I get this message: “The disc wasn’t ejected because one or more programs may be using it.” This happens even if there is no backup occurring.

Only option is to Force Eject. No clue why this changed or how to fix it. Currently running Tahoe 26.5.2.

Yes there have been some issue here in Tahoe 26.5.2

you can see what is the dissenter from the Terminal.app copy and paste this line:

diskutil eject 

Notice the trailing blank space,

now drag and drop your Time Machine desktop icon directly onto the Terminal window to complete the path

ex.

MacBook-Pro ~ % diskutil eject /Volumes/untitled

Unmount of disk14 failed: at least one volume could not be unmounted

Unmount was dissented by PID 1821 (/System/Library/PrivateFrameworks/SystemMigration.framework/Versions/A/Resources/systemmigrationd)

Dissenter parent PPID 1 (/sbin/launchd)

You see the culprit here is "systemmigrationd" —yours may well be something different.

this can then be followed by

sudo kill 1821 && diskutil eject /Volumes/untitled

( your psswd will not echo on screen, type it in anyway, to proceed use the enter\return key)