Can't unmount external disk used with Music app due to AMPLibraryAgent process 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?
You can try force unmounting the drive. It unmounts the drive if some process is already using it.

diskutil unmountdisk force /dev/disk2