When trying to eject a disk, e.g. an external volume, via Finder then sometimes macOS is not able to name the exact application still accessing files

Ejecting disk in macOS blocked by «one or more apps using it»? Find that App!

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2025-01-22 08:00:08

When trying to eject a disk, e.g. an external volume, via Finder then sometimes macOS is not able to name the exact application still accessing files on that disk – and leaves you wondering with a rather generic message: «One or more apps are using it». But we also learned that force-ejecting disks is a big No-No.

Back in the day there was a neat tool «What’s keeping me?» that gave you a simple UI to quickly list all programs accessing and blocking open files on a volume, and closing them. In the meantime this app is no longer supporting modern macOS versions – and the UI-driven help even provided by Apple Support won’t do the job either, as sometimes a background-process has files open on the affected volume.

Here’s a step-by-step guide to find & close apps or processes, that still access files on a disk, in order to unblock the disk to be ejectable again.

This is a solid and compatible way for many macOS-versions. Unfortunately it means to resort to the technical Unix Terminal.app on your Mac. Optionally however you can use it in combination with Activity Monitor.app.