rust-lang/cargo · error

`[project]` is not supported as of the 2024 Edition, please…

Error message

`[project]` is not supported as of the 2024 Edition, please use `[package]`

What it means

Thrown when a manifest contains a [project] section and the resolved edition is 2024 or later. Historically [project] was an alias for [package]; as of the 2024 edition it is removed entirely (a hard error). For editions before 2024, the same condition only emits a deprecation warning. The check uses original_toml.project.is_some() and compares Edition::Edition2024 <= edition.

Solutions

1. Rename the [project] section header to [package] in Cargo.toml.
2. If a tool generated the manifest, update its template to use [package].
3. Run `cargo fix --edition` to migrate legacy fields when bumping editions.

Example fix

# before
[project]
name = "my-crate"
version = "0.1.0"
edition = "2024"

# after
[package]
name = "my-crate"
version = "0.1.0"
edition = "2024"

fn check_no_project_section_on_2024(toml: &str) -> Result<(), String> {
    let v: toml::Value = toml::from_str(toml).map_err(|e| e.to_string())?;
    let edition = v.get("package").or_else(|| v.get("project"))
        .and_then(|p| p.get("edition")).and_then(|e| e.as_str())
        .unwrap_or("2015");
    if v.get("project").is_some() && edition >= "2024" {
        return Err("rename [project] to [package] for edition 2024".into());
    }
    Ok(())
}

fn uses_package_not_project(toml: &toml::Value) -> bool {
    toml.get("project").is_none() || toml.get("package").is_some()
}

When it happens

Trigger: A Cargo.toml with edition = "2024" (or unspecified defaulting to 2024) that uses [project] instead of [package]. Triggered during to_real_manifest validation.

Common situations: Upgrading a crate's edition to 2024 without renaming [project] to [package]. Very old manifests that predate the [package] standardization. Templates that still emit [project].

Related errors

• ` ` is unsupported as of the 2024 edition; instead use `…
• manifest is missing either a `[package]` or a `[workspace]`
• can only edit absolute paths, got
• can't find library ` `, rename file to `src/lib.rs` or…
• cannot mix `proc-macro` crate type with others

AI-assisted analysis of rust-lang/cargo@98a09e7e7d (2026-08-11). Data as JSON: /api/errors/7ecf1711521411b5. Report an issue: GitHub.

Appendix: source

Thrown at src/workspace/parser/mod.rs:1395

            ));
        }
        default_edition
    };
    if !edition.is_stable() {
        let version = normalized_package
            .normalized_version()
            .expect("previously normalized")
            .map(|v| format!("@{v}"))
            .unwrap_or_default();
        let hint = rust_version
            .as_ref()
            .map(|rv| format!("help: {package_name}{version} requires rust {rv}"));
        features.require_with_hint(Feature::unstable_editions(), hint.as_deref())?;
    }

    if original_toml.project.is_some() {
        if Edition::Edition2024 <= edition {
            anyhow::bail!(
                "`[project]` is not supported as of the 2024 Edition, please use `[package]`"
            );
        } else {
            warnings.push(format!("`[project]` is deprecated in favor of `[package]`"));
        }
    }

    if normalized_package.metabuild.is_some() {
        features.require(Feature::metabuild())?;
    }

    if is_embedded {
        let manifest::TomlManifest {
            cargo_features: _,
            package: _,
            project: _,
            badges: _,
            features: _,

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