These are probably different kind of "errors" than what the author of this article is talking about. The kind of errors you'll see are dropped network connectio

These are probably different kind of "errors" than what the author of this article is talking about. The kind of errors you'll see are dropped network connections, malformed data, and stuff like that which is basically impossible to prevent because it's an imperfect universe. Even at a fairly small scale you will see "errors" of this kind regardless – you don't need to be a huge CDN for that. But what the author is talking about – in my reading anyway – is programming errors: exceptions, out of bounds access, explicit report_error() calls, things like that which will result in 5xx errors for the client. You've got a lot more control over that. Sometimes random failures beyond your control will cause a 5xx error, and IMHO that's a bug and this usually should be a 4xx or something else (e.g. if the client sends wrong or junk data you shouldn't respond with a 5xx). I suppose that's the corollary to this article: not all "errors" are the same, and you should distinguish between different types of errors.