The error seems appropriate: the client expects erroneously something from the server that it can't provide (otherwise there would be something other than the default page to return)
I mean sure, but it feels like a stretch (albeit a whimsical one) to say its more appropriate than 404 Not Found, which could also be described as "client expects erroneously something from the server that it can't provide".
Maybe 405 or 406 then? I mean, sure it's not right either, but better than 418? (I'd say go with 404.)
The client is mistaken in requesting coffee.
HTTP 420 Enhance your calm
HTTP 527 Railgun Listener to Origin
That one's not standard, and probably shouldn't ever have been used in the first place IMO
Neither is 420
This one actually gets use. I bumped up against an error in our internal services and it was returning 420's... Not fun to diagnose
Don’t give Elon any ideas
I think twitter is where it was first used, actually. They stopped after a while, but from what I read, it was a code you got before hitting your API limit. (iirc, you got a 417/429 error when you ran out)