Error page

An error page is not a component, it is a whole screen standing in for a screen that could not be built. Two things have to happen on it and everything else is decoration: the reader learns what happened without being told it was their fault, and they are handed the shortest route back to something that works. A search box, one or two links to the places most people were probably heading, and little else. The page is a dead end by definition, so its only real job is to stop being one.

Two different failures wear this page and want opposite answers. A not-found page means the reader asked for something that is not here, usually from an old link or a mistyped address, and the way out is to navigate: the page says the address does not lead anywhere and offers the search and the home page. A server error page means the site itself is broken, the reader did nothing at all, and navigating is useless because the next page may fail the same way. Its way out is to wait, ideally with a time to come back and somewhere to report it, which is why the GOV.UK Design System keeps its “problem with the service” pattern separate from its page-not-found one.

Then the disagreement, which is real and has citations on both sides. The Nielsen Norman Group’s advice, first published in 1998 and still repeated, is to mitigate total failure with novelty: a joke, an illustration, something that makes a dead end forgivable. The GOV.UK Design System says the opposite outright. No informal language on a page-not-found page, no red warning text, and never print the number 404, because someone filing a tax return did not come for a cartoon and does not know what 404 means. Both are right about their own reader. Novelty pays where the visit is discretionary and the stakes are low, so a magazine, a studio site or a personal project can afford charm. It costs where the reader is transacting under obligation or under stress, and the only kindness left is being brief and plain. The question is not taste, it is whether your reader chose to be here.

Technically it is one page under two contracts. The status code has to be the real one, because a friendly page served as 200 tells search engines and monitoring that the request succeeded, and the copy has to work for a reader who has never heard of a status code. What this word is not: an error message is the line attached to one field, an error summary is the block at the top of a form that failed, a no results state is a search that matched nothing inside a page that worked perfectly, and an empty state is a container with nothing in it yet. All four happen on a page that loaded. This one replaced the page.