Strange. All of a sudden, I can't move files on my external drives to the trash — I get a warning that they'll be deleted immediately.
Disk Utility's First Aid fails because it can't unmount the drive, but DiskWarrior reports the SMART status as being fine.
Also, one of the drives is 1 day old…
Might have to reboot. Again. 4 hours after the last reboot. Sigh.