#fs #err #error


A drop-in replacement for std::fs with more helpful error messages

14 releases (stable)

2.7.0 Feb 19, 2022
2.6.0 May 6, 2021
2.5.0 Sep 27, 2020
2.3.0 Mar 17, 2020
0.1.2 Feb 10, 2020

#25 in Filesystem

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fs-err is a drop-in replacement for std::fs that provides more helpful messages on errors. Extra information includes which operations was attempted and any involved paths.

Error Messages

Using std::fs, if this code fails:

let file = File::open("does not exist.txt")?;

The error message that Rust gives you isn't very useful:

The system cannot find the file specified. (os error 2)

...but if we use fs-err instead, our error contains more actionable information:

failed to open file `does not exist.txt`
    caused by: The system cannot find the file specified. (os error 2)


fs-err's API is the same as std::fs, so migrating code to use it is easy.

// use std::fs;
use fs_err as fs;

let contents = fs::read_to_string("foo.txt")?;

println!("Read foo.txt: {}", contents);

fs-err uses std::io::Error for all errors. This helps fs-err compose well with traits from the standard library like std::io::Read and crates that use them like serde_json:

use fs_err::File;

let file = File::open("my-config.json")?;

// If an I/O error occurs inside serde_json, the error will include a file path
// as well as what operation was being performed.
let decoded: Vec<String> = serde_json::from_reader(file)?;

println!("Program config: {:?}", decoded);


Licensed under either of

at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

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