external hard drives can't be safely ejected because used by system

Unless you enter the drive in System Settings > Spotlight > Privacy, you risk Spotlight indexing the drive when you want to eject it and you won't be able to because the drive is in use by a system process.

That's one issue. If you launched an application to access a file on that external drive and did not close and quit that Application, then the drive will still register as in use, and eject will fail.

Any Finder window open on that external drive, or any Terminal application that has changed the directory or is accessing files on that external drive will prevent a successful eject as they keep the drive in use.

NicolasRouleau wrote:

Hi,

I use external hard drives to work. A few times now the system has refused to eject the drives stating that an app was using the drives, without saying which one. Does it even if all apps are closed.

Apps are never closed. They are constantly running in the background.

Any idea of the cause?

Some background app is using the drive.

You can add the drive to Spotlight Privacy in System Settings > Spotlight. That will (might) keep Spotlight from using the drive. If all else fails, you can shutdown the computer and then safely remove the drive.

There are reports related to macOS 15 Sequoia and External Drives being problematic when attempting to " external hard drives can't be safely ejected "

Having experienced the same issue on a M4 Desktop with version 15.2

I came across this interesting article from Carbon Copy Cloner

https://support.bombich.com/hc/en-us/articles/20686422368663-Why-can-t-I-eject-the-destination-volume-after-the-backup-task-has-completed

Specifically the subsection related to " Attempt to unmount " and " Finding the offending file and application " and

" It's usually Spotlight "

In my specific case, while using CCC on an external SSD Drive to Clone / Backup the computer

The drive just would not unmount

Resorted to reformatting the drive and setting it up anew in CCC and it worked

When that happens to me I go Cmd-Opt-Esc (as it to Force Quit something), select the Finder, and then Relaunch the Finder.

That usually sorts it out.

Relaunching Finder does not work nor does adding to Spotlight privacy since it will not add - this happens every time with every removeable drive. I want to uninstall Sequoia as it does NOTHING but cause problems.