This article from BurntSushi is still probably the best resource on error handling best practices. Essentially, we want to provide our own concrete error type(s) whenever returning an error. The Error trait in the standard library was fixed semi-recently, so it makes sense to define our own custom error type and implement Error for it. The best crate I can see currently for doing that is err-derive, which extracts the custom derive logic from failure and applies it to the std Error trait. Using that, we could create our own custom error types while still doing so in a way that's compatible with the rest of the Rust ecosystem. err-derive in combination with the derive_more (which provides the ability to derive From impls) would make it really easy to build custom error types.