rust-lang/cargo · error

unrecognized feature{} for crate {}: {}

Error message

unrecognized feature{} for crate {}: {}

What it means

`cargo add` validates requested feature names against the set of features the chosen crate actually exposes (from its index summary or manifest). If any requested feature (including inherited ones) is not in `dep.available_features`, the operation is aborted. The message lists the unknown features and, when possible, appends edit-distance suggestions and the available enabled/disabled feature sets to help correct the typo.

Source

Thrown at src/ops/cargo_add/mod.rs:239

                                .map(|s| s.to_string())
                                .coalesce(|x, y| if x.len() + y.len() < 78 {
                                    Ok(format!("{x}, {y}"))
                                } else {
                                    Err((x, y))
                                })
                                .into_iter()
                                .format("\n    ")
                        )?;
                    } else {
                        writeln!(
                            message,
                            "\n\n{} enabled features available",
                            activated.len()
                        )?;
                    }
                }
            }
            anyhow::bail!(message.trim().to_owned());
        }

        print_dep_table_msg(&mut options.gctx.shell(), &dep)?;

        manifest.insert_into_table(
            &dep_table,
            &dep,
            workspace.gctx(),
            workspace.root(),
            options.spec.manifest().unstable_features(),
        )?;
        if dep.optional == Some(true) {
            let is_namespaced_features_supported =
                check_rust_version_for_optional_dependency(options.spec.rust_version())?;
            if is_namespaced_features_supported {
                let dep_key = dep.toml_key();
                if !manifest.is_explicit_dep_activation(dep_key) {
                    let table = manifest

View on GitHub (pinned to 0e07a15537)

Solutions

1. Re-read the error's printed feature list and pick the exact spelling it suggests (it includes edit-distance suggestions).
2. Check the selected crate version's feature list: `cargo add <crate> --dry-run` or consult `docs.rs/<crate>` for that version.
3. Pin to a version known to expose the feature (`cargo add <crate>@<version> --features <name>`) or drop the unknown feature.

Example fix

# before
cargo add serde --features derivee

# after
cargo add serde --features derive

// Fetch available features from the registry metadata and diff before invoking add.
// Pseudocode using `crates_io_api` or `cargo metadata`:
fn validate_features(crate_name: &str, version: &str, wanted: &[String]) -> Result<(), Vec<String>> {
    let available: Vec<String> = fetch_features(crate_name, version); // your lookup
    let unknown: Vec<_> = wanted.iter().filter(|f| !available.contains(f)).cloned().collect();
    if unknown.is_empty() { Ok(()) } else { Err(unknown) }
}

When it happens

Trigger: Running `cargo add serde --features derivee` (typo) or passing a feature that exists in a different version than the one selected, e.g. `cargo add tokio --features full` against a tokio version that lacks `full`. Both `dep.features` and `dep.inherited_features` are diffed against `available_features` at mod.rs:148-157.

Common situations: Feature renamed or removed between crate versions (e.g. a 0.x crate restructured its features), case mistakes (`--features Default`), hyphen/underscore confusion, or copying a feature list from outdated documentation.

Related errors

• manifest validated
• not implemented
• feature `{feature}` must be qualified by the dependency it's
• feature `{feature}` is not allowed to use explicit `dep:` sy
• `{feature}` is unsupported when inferring the crate name, us

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/4850b3821417a768.json. Report an issue: GitHub.