I use an external storage disk for my Music library in macOS 10.15 Catalina, because the required file size is several times my internal SSD. After upgrading to Catalina, now when I connect the drive to use Music, I cannot eject the drive afterward, due to a lock by the AMPLibraryAgent process. Here is terminal output detailing the issue:

diskutil unmountdisk /dev/disk2
Unmount of disk2 failed: at least one volume could not be unmounted
Unmount was dissented by PID 710 (/System/Library/PrivateFrameworks/AMPLibrary.framework/Versions/A/Support/AMPLibraryAgent)
Dissenter parent PPID 1 (/sbin/launchd)

How can I remove this lock without quitting that service process or shutting down my computer?

  • What’s preventing you to quit the process, unmount the volume and restart the process? – Naveed Abbas Oct 16 at 17:51
  • @NaveedAbbas It’s out of scope of my question – jsejcksn Oct 16 at 19:11
  • I am willing to force the unmount--you can do this from the GUI, too--but I want to know is what danger there is if I force it. The developers are assuming that this process needs to run and that it's bad to unmount a disk while it is. They should have provided a way to stop it cleanly. As it is, we don't know whether forcing the umount loses some data or something else undesirable. On my system, it seems to be seems to be the Music app that sometimes causes AMPLibraryAgent to run, since that's what I use the external disk for. Why? – Mars Nov 1 at 1:44

You can try force unmounting the drive. It unmounts the drive if some process is already using it.

diskutil unmountdisk force /dev/disk2
  • This does not address the question, which is "How can I remove this lock without quitting that service process or shutting down my computer?" – jsejcksn Oct 25 at 19:14

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