axum-core-router

Axum 0.8 panics on startup if you use old 0.7 path syntax like :id or *path. You must migrate to the new {id} and {*path} syntax to prevent deliberate startup panics.

To get correct 404 vs 405 behavior in Axum, apply proper fallback and fallback-reset rules. This ensures unmatched paths return 404 while wrong-method requests return 405.

.layer applies middleware to all requests including fallbacks, while .route_layer targets only matched routes. Correct placement prevents real 404s from turning into unexpected auth errors.

Correct Axum routing composition requires choosing between .route, .nest, .merge, and nest_service carefully. This ensures handlers land at the right paths and methods without precedence overlap.

No, Axum 0.8 deliberately panics if you use the :id syntax. You must migrate path parameters to the new curly brace syntax like {id} and {*path} to achieve version compatibility.

Avoid .merge when route precedence and overlap avoidance are critical, as it flattens paths and can obscure handler matching. Using .nest with deterministic configuration prevents incorrect HTTP routing outcomes.