Ehh, that really feel like "But other people do it wrong too" to me, half the 4xx error codes are application layer errors for example (404 ain't a transport layer error, neither is 403, 415, 422 or 451)

It also complicates actually processing the request as you've got to duplicate error handling between "request failed" and "request succeeded but actually failed". My local cinema actually hits that error where their web frontend expects the backend to return errors, but the backend lies and says everything was successful, and then certain things break in the UI.

[–] luciferofastora@feddit.org 1 points 1 hour ago

frontend expects the backend to return errors, but the backend lies and says everything was successful, and then certain things break in the UI

That's a double failure then: not only does the backend do it wrong, the frontend devs don't even know it. If they'd agreed on one way of handling it, they'd still be able to work it out. But if the devs don't even communicate their standards with each other and the frontend devs obviously don't know about the problem...