Custom Error Pages

Covers all three scenarios from the official tutorial: 404s have two supported approaches; 500s have exactly one (unhandled exceptions bypass Umbraco's routing pipeline, so only a plain MVC controller works — see 500-error-controller.md, shared by both approaches); Boot Failed has one trivial method (see below).

Looking for a maintenance page (shown during Umbraco upgrades)? That's not an error page — use the separate umbraco-custom-maintenance-page skill instead.