Well, Rust's standard library provides two types named Error, their full names are core::fmt::Error (aka std::fmt::Error) and std::io::Error

But, neither of these is intended as "the" error type - unless you're a formatter or an I/O abstraction they're not the error types you want.

Rust provides a trait core::error::Error (aka std::error::Error) and that might be what you're thinking about. It's recommended that your own private error type or types should implement this trait but nothing requires this in most contexts.