Regarding the author's recommendation against using 404: The author says it's ambiguous, because it could mean the route is not found, or it could mean the requested item is not found. Some people use 204 to indicate the latter: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/204 It basically means, "We received and understood your request, but you're not getting a response." And you can infer that it's beca…
As an alternative to using HTTP 404 for detecting a misconfigured server with bad routing, you could use the "Server" response header to include an invariant indicator as a confidence sign to the client that the HTTP 404 response does not mean bad-routing or misconfigured server - or expired-domain-name-now-points-to-a-domain-squatting-website.
[1] https://developer.mozilla.org/en-US/docs/Web/API/Navigator/s...