Understanding Rust Error E0464: Multiple Library Files Found

Introduction to Rust Error E0464

Rust Error E0464 occurs when the compiler detects multiple library files with the same requested crate name without a clear indication of which library file to use. This error often results from using 'extern crate' or supplying '--extern' options without specifying the complete crate paths, and it may also stem from caching issues in the build directory.

Example of Rust Error E0464

// aux-build:crateresolve-1.rs
// aux-build:crateresolve-2.rs
// aux-build:crateresolve-3.rs

extern crate crateresolve;
//~^ ERROR multiple candidates for `rlib` dependency `crateresolve` found

fn main() {}

In this example, three different library files define the same crate name 'crateresolve'. Without a full path specified, the compiler cannot determine which crate to use, resulting in Rust Error E0464.

Resolving Rust Error E0464

To resolve Rust Error E0464, follow these steps:

1. Specify the full path using the 'extern crate' syntax:

extern crate my_library as my_library_target;

// Use 'my_library_target' in your code

2. Try running 'cargo clean' to resolve potential caching issues in the build directory.

3. If the error persists, review your library files to ensure that only the necessary ones are included in the build and that each library has a unique name.


Understanding and resolving Rust Error E0464 is essential for avoiding conflicts between crates and ensuring a successful build process. By following the steps outlined in this article, you can prevent multiple library files from causing this error and maintain an efficient, error-free development environment.