Empirically, that's probably true, but probably only because functional programming is usually more popular with fiddlers and academics than with get-shit-done

Empirically, that's probably true, but probably only because functional programming is usually more popular with fiddlers and academics than with get-shit-done developers, so there's simply less time spent on improving developer experience. I can't think of any inherent reason why functional languages would have worse error messages. Elm prides itself in its (compiler) error messages, for instance: http://elm-lang.org/blog/compilers-as-assistants http://elm-lang.org/blog/compilers-as-assistants