This is probably another mpd (or systemd socket?) already running. It would be useful if you could provide more detail on how you're starting mpd (initscript/systemd/as user/...) and whether this was really the first intall of mpd on your machine?
This is probably another mpd (or systemd socket?) already running. It would be useful if you could provide more detail on how you're starting mpd (initscript/ systemd/ as user/...) and whether this was really the first intall of mpd on your machine?