Unfortunately - losing the physical drive did not invalidate the file handle, and I suspect that Apple Isn’t doing things right there in some cases. Start writing to a physically attached device - USB, TB, etc.) and pull the plug on the drive. I’ve found that Apple handles that fairly well. A network attached volume, on the other hand, doesn’t have a physical layer for the kernel to interact with, so if the file handler for the filesystem being used isn’t set up to handle the loss of the path, that could cause a crash as the app tries to write to a no-longer mapped file handle. I would be curious if the user’s system was using an Apple API or an API provided by the remote hosting service. We also see this type of unhandled event with a lot of FUSE layer filesystems - such as LTFS. We can cause Finder to glitch completely when copying files to an LTFS tape.