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

manifest path `{}` is a directory but expected a file{sugges

Error message

manifest path `{}` is a directory but expected a file{suggested_path}

What it means

root_manifest checks that `--manifest-path` exists and is NOT a directory. If the path is a directory, Cargo bails and, when a `Cargo.toml` child exists inside it, appends a help line suggesting that file. Cargo expects a file path, not a folder.

Source

Thrown at src/util/command_prelude.rs:1064

    args._values_of_os(name)
}

pub fn root_manifest(manifest_path: Option<&Path>, gctx: &GlobalContext) -> CargoResult<PathBuf> {
    if let Some(manifest_path) = manifest_path {
        let path = gctx.cwd().join(manifest_path);
        // In general, we try to avoid normalizing paths in Cargo,
        // but in this particular case we need it to fix #3586.
        let path = paths::normalize_path(&path);
        if !path.exists() {
            anyhow::bail!("manifest path `{}` does not exist", manifest_path.display())
        } else if path.is_dir() {
            let child_path = path.join("Cargo.toml");
            let suggested_path = if child_path.exists() {
                format!("\nhelp: {} exists", child_path.display())
            } else {
                "".to_string()
            };
            anyhow::bail!(
                "manifest path `{}` is a directory but expected a file{suggested_path}",
                manifest_path.display()
            )
        } else if !path.ends_with("Cargo.toml") && !crate::workspace::parser::is_embedded(&path) {
            if gctx.cli_unstable().script {
                anyhow::bail!(
                    "the manifest-path must be a path to a Cargo.toml or script file: `{}`",
                    path.display()
                )
            } else {
                anyhow::bail!(
                    "the manifest-path must be a path to a Cargo.toml file: `{}`",
                    path.display()
                )
            }
        }
        if crate::workspace::parser::is_embedded(&path) && !gctx.cli_unstable().script {
            anyhow::bail!("embedded manifest `{}` requires `-Zscript`", path.display())

View on GitHub (pinned to 0e07a15537)

Solutions

  1. Append `Cargo.toml`: `cargo build --manifest-path ./mycrate/Cargo.toml`.
  2. If the help line suggests a path, use exactly that path.
  3. Drop `--manifest-path` and `cd` into the directory so Cargo auto-discovers Cargo.toml.

Example fix

# before
cargo build --manifest-path ./mycrate

# after
cargo build --manifest-path ./mycrate/Cargo.toml
Defensive patterns

Strategy: validation

Validate before calling

use std::path::Path;
fn ensure_manifest_is_file(p: &Path) -> Result<(), anyhow::Error> {
    if !p.exists() { anyhow::bail!("{p:?} missing"); }
    if p.is_dir() { anyhow::bail!("{p:?} is a directory; append Cargo.toml"); }
    Ok(())
}

Type guard

fn is_manifest_file(p: &std::path::Path) -> bool {
    p.is_file() && p.file_name().map(|n| n == "Cargo.toml").unwrap_or(false)
}

Try / catch

match root_manifest(Some(path), gctx) {
    Err(e) if e.to_string().contains("is a directory") => {
        eprintln!("pass the Cargo.toml file, not its directory");
        return Err(e);
    }
    r => r,
}

Prevention

When it happens

Trigger: Passing a directory to `--manifest-path`: `cargo build --manifest-path ./mycrate` where `mycrate/` is a folder (commonly one that contains a Cargo.toml).

Common situations: Pointing `--manifest-path` at the crate directory rather than its Cargo.toml; muscle memory from tools that accept a directory; scripts that pass `${PROJECT_DIR}` instead of `${PROJECT_DIR}/Cargo.toml`.

Related errors

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/3efbb459fb3d482a.json. Report an issue: GitHub.