So this error is really frustrating, because I remember encountering it once, doing something to fix it, and then forgetting what I did. The error it’s signaling acts like it’s part of the lilypond init file, which isn’t part of scamp or even abjad. So I’m not sure what the deal is; maybe you start by checking if abjad works on its own:
import abjad
abjad.show(abjad.Note("c'"))
Does this throw an error?