rust-lang/cargo · error · anyhow::Error

patch for `{}` in `{}` resolved to more than one candidate n

Error message

patch for `{}` in `{}` resolved to more than one candidate
note: found versions: {}
help: check `{}` patch definition for `{}` in `{}`
help: select only one package using `version = "={}"`

What it means

Error "patch for `{}` in `{}` resolved to more than one candidate note: found versions: {} help: check `{}` patch definition for `{}` in `{}` help: select only one package using `version = "={}"`" thrown in rust-lang/cargo.

Source

Thrown at src/workspace/registry.rs:959

    locked: &Option<LockedPatchDependency>,
    mut summaries: Vec<Summary>,
    source: &dyn Source,
) -> CargoResult<(Summary, Option<PackageId>)> {
    if summaries.len() == 1 {
        return Ok((summaries.pop().unwrap(), None));
    }
    if summaries.len() > 1 {
        // TODO: In the future, it might be nice to add all of these
        // candidates so that version selection would just pick the
        // appropriate one. However, as this is currently structured, if we
        // added these all as patches, the unselected versions would end up in
        // the "unused patch" listing, and trigger a warning. It might take a
        // fair bit of restructuring to make that work cleanly, and there
        // isn't any demand at this time to support that.
        let mut vers: Vec<_> = summaries.iter().map(|summary| summary.version()).collect();
        vers.sort();
        let versions: Vec<_> = vers.into_iter().map(|v| v.to_string()).collect();
        return Err(anyhow::anyhow!(
            "patch for `{}` in `{}` resolved to more than one candidate\n\
            note: found versions: {}\n\
            help: check `{}` patch definition for `{}` in `{}`\n\
            help: select only one package using `version = \"={}\"`",
            &original_patch.dep.package_name(),
            &original_patch.dep.source_id(),
            versions.join(", "),
            &original_patch.dep.package_name(),
            orig_patch_url,
            original_patch.loc,
            versions.last().unwrap()
        ));
    }
    assert!(summaries.is_empty());
    // No summaries found, try to help the user figure out what is wrong.
    if let Some(locked) = locked {
        // Since the locked patch did not match anything, try the unlocked one.
        let orig_matches = source

View on GitHub (pinned to 0e07a15537)

Solutions

1. Narrow the patch with `version = "=<version>"` so it selects exactly one candidate.
2. Remove duplicate packages from the patch location.

When it happens

Trigger: Thrown at src/workspace/registry.rs:959 when the library encounters an invalid state.

Common situations: Occurs when a `[patch]` entry matches multiple candidate versions at its location. Constrain the patch with an exact version, e.g. `version = "=1.2.3"`, so only one candidate matches.

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/24a764135e223c78.json. Report an issue: GitHub.