BoundaryML/baml · error

Failed to load cargo metadata: {e}

Error message

Failed to load cargo metadata: {e}

What it means

load_metadata runs cargo_metadata's MetadataCommand for the selected manifest and panics if cargo metadata execution fails, with the underlying cargo_metadata error embedded in the message. The tool treats resolvable workspace metadata as a hard precondition for all subsequent stow operations.

Source

Thrown at baml_language/crates/tools_stow/src/main.rs:608

fn find_crate_dirs(crates_dir: &Path) -> Vec<PathBuf> {
    let mut dirs = Vec::new();
    if let Ok(entries) = std::fs::read_dir(crates_dir) {
        for entry in entries.flatten() {
            let path = entry.path();
            if path.is_dir() && path.join("Cargo.toml").exists() {
                dirs.push(path);
            }
        }
    }
    dirs.sort();
    dirs
}

fn load_metadata(manifest_path: &Path) -> cargo_metadata::Metadata {
    MetadataCommand::new()
        .manifest_path(manifest_path)
        .exec()
        .unwrap_or_else(|e| panic!("Failed to load cargo metadata: {e}"))
}

fn toml_array_strings(value: Option<&toml::Value>) -> Vec<String> {
    value
        .and_then(|v| v.as_array())
        .map(|arr| {
            arr.iter()
                .filter_map(|v| v.as_str().map(std::string::ToString::to_string))
                .collect::<Vec<String>>()
        })
        .unwrap_or_default()
}

fn derive_member_roots(workspace_root: &Path, members: &[String]) -> Vec<PathBuf> {
    let mut roots = Vec::new();
    let mut seen = HashSet::new();

    for member in members {

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Run `cargo metadata --manifest-path <path>` manually to surface the real cargo error and fix it.
2. Confirm you are invoking stow from inside the intended cargo workspace.
3. Ensure a working cargo toolchain is on PATH (rustup default stable; rustup update).
4. If a dependency resolution issue, update the lockfile (cargo update) or fix the dependency spec.

Example fix

// before: stow fails in CI with no cargo\n- run: cargo run -p tools_stow -- stow\n// after: install toolchain first\n- run: dtolnay/rust-toolchain@stable\n- run: cargo run -p tools_stow -- stow

let out = std::process::Command::new("cargo")\n    .args(["metadata","--manifest-path",manifest_path.to_str().unwrap()])\n    .output()?;\nif !out.status.success() { panic!("workspace metadata unresolvable before running stow"); }

match MetadataCommand::new().manifest_path(manifest_path).exec() {\n    Ok(m) => m,\n    Err(e) => { eprintln!("Failed to load cargo metadata: {e}"); std::process::exit(1); }\n}

When it happens

Trigger: main() calls load_metadata with the chosen manifest path; MetadataCommand::exec() returns Err when cargo metadata cannot run or the manifest cannot be resolved.

Common situations: Running stow outside a valid cargo workspace; corrupt Cargo.toml/lockfile; incompatible rustup toolchain; virtual manifest requiring features the resolver rejects; PATH without cargo in the CI environment.

Understand the failure class

Background: "API request failed": what wrapped HTTP errors from external APIs mean and how to find the real cause — this error's family across 29 libraries.

Related errors

• cargo metadata failed
• cargo build failed for {package}
• cargo build failed for pack ({} + {})
• cargo metadata failed
• package '{package_name}' not found in cargo metadata

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/99616e3312abd72f. Report an issue: GitHub.