linera-io/linera-protocol · error · anyhow::Error

No Cargo.toml found at {}. The path must point to a Rust pro

Error message

No Cargo.toml found at {}. The path must point to a Rust project directory.

What it means

Project::from_existing_project treats the given path as a Rust project root and requires a Cargo.toml there. Without a manifest the path is not a Cargo project, so building the application's WASM contract and service is impossible and the call fails.

Source

Thrown at linera-service/src/project.rs:94

        debug!("Writing service.rs");
        Self::create_service_file(&source_directory, name)?;

        debug!("Writing single_chain.rs");
        Self::create_test_file(&test_directory, name)?;

        Ok(Self { root })
    }

    /// Opens an existing application project at the given root directory.
    pub fn from_existing_project(root: &Path) -> Result<Self> {
        let root = root.canonicalize().with_context(|| {
            format!(
                "Could not find project at {}. \
                 Make sure the specified directory exists.",
                root.display()
            )
        })?;
        ensure!(
            root.join("Cargo.toml").exists(),
            "No Cargo.toml found at {}. \
             The path must point to a Rust project directory.",
            root.display()
        );
        Ok(Self { root })
    }

    /// Runs the unit and integration tests of an application.
    pub fn test(&self) -> Result<()> {
        let tests = Command::new("cargo")
            .arg("test")
            .args(["--target", CURRENT_PLATFORM])
            .current_dir(&self.root)
            .spawn()?
            .wait()?;
        ensure!(tests.success(), "tests failed");
        Ok(())

View on GitHub (pinned to 6c226ddcb3)

Solutions

1. Pass the directory that actually contains Cargo.toml — usually your application's crate root
2. Verify with `ls <path>/Cargo.toml` before running the command
3. If the project does not exist yet, create it first with `linera project new`

Example fix

# before
$ linera project publish ./my-dapp/src
error: No Cargo.toml found at my-dapp/src ...

# after
$ linera project publish ./my-dapp

let manifest = path.join("Cargo.toml");
if !manifest.exists() {
    anyhow::bail!("not a Rust project (no Cargo.toml at {})", path.display());
}

fn is_rust_project(path: &std::path::Path) -> bool {
    path.join("Cargo.toml").exists()
}

When it happens

Trigger: `linera project publish <path>` (or any from_existing_project caller) where <path>/Cargo.toml does not exist: wrong directory, a typo in the path, or a non-Rust project.

Common situations: Running publish from the wrong cwd or pointing at the source subdir (src/) or build output instead of the crate root; the project was never scaffolded with `linera project new`.

Related errors

• Project name {name} should not contain path-separators
• Project name {name} should not have a file extension
• tests failed
• build failed
• Only allowed options are grpc and grpcs

AI-assisted analysis of linera-io/linera-protocol@6c226ddcb3 (2026-08-22). Data as JSON: /api/errors/d30adc4deaff6700. Report an issue: GitHub.