I am getting an "There was a temporary problem completing your request. An unknown error occurred (-50).

My wife randomly gets this error popping up every day. It is not connected to anything she is doing (that she can tell). She no longer has iTunes installed, but she does still have iTunes media folders on her computer. She uses Music extensively as she is a choreographer and Music Theater performance instructor. We have a Family Music subscription and she has an extensive library of purchased music. But she doesn't use the cloud or back up to the cloud as it has a tendency to disappear music files she purchased and downloaded from iTunes or Apple Music or copied from CDs (remember those?).

I suspect it has something to do with the fact that she doesn't let her Music upload music or playlists to iCloud, but wondered if there was anyone here more experienced than the Apple genius experts I have already talked to. They seemed to be mystified by the random ghosting of music files and the error messages that are typically connected to the iTunes app which is not installed.