Axum is a web framework for Rust built on top of Tokio and Hyper. One of its standout features is a simple and predictable error handling model — once you understand the pattern, writing safe, expressive web servers becomes surprisingly natural. This guide walks you from the very basics to real-world patterns you'll use in production. The Core Idea: Errors Must Become Responses In Axum, every error must eventually become an HTTP response . There is no unhandled-exception mechanism. If something goes wrong, you decide what the client sees — a 404, a 500, a JSON error body, or anything else. The key trait is IntoResponse . Anything that implements it can be returned from a handler, including error types. 1. The Simplest Error: Return a StatusCode The easiest way to signal an error is to return a StatusCode directly.…