Moral error theory, the view that moral discourse is factually defective, is an influential view in contemporary metaethics. Although it has long been recognized that the arguments for this view might generalize and apply to other domains than the moral, it has traditionally been understood, defended, and evaluated as confined to the moral domain. This has begun to change. In order to see whether the arguments for moral error theory generalize beyond the moral domain, I first formulate an argument for the view, which targets what error theorists usually attempt to capture – the authority of moral reasons. I argue that the resulting metaethical view is plausible, especially when compared to its main competitors. I then go on to show that most arguments for moral error theory, including the one I have presented, generalize to target all of irreducible normativity. Most moral error theorists should therefore become metanormative error theorists. To explore the consequences of this generalization I show that at least two non-moral normative discourses are also committed to irreducible normativity, namely those concerning practical and epistemic reasons. I conclude by evaluating the plausibility of a metanormative error theory that holds not only moral but also practical and epistemic discourses to be factually defective.