clockworklabs/SpacetimeDB · error · anyhow::Error

Could not detect the language of the module. Are you in a Sp

Error message

Could not detect the language of the module. Are you in a SpacetimeDB project directory?

What it means

Thrown by detect_module_language when the module directory exists but contains none of the markers the CLI recognizes: Cargo.toml (Rust), any *.csproj (C#), package.json (JavaScript/TypeScript), or CMakeLists.txt (C++). Without a marker the CLI cannot decide which toolchain to use to build the module.

Source

Thrown at crates/cli/src/util.rs:284

        );
    }
    // check for Cargo.toml
    if path_to_module.join("Cargo.toml").exists() {
        Ok(ModuleLanguage::Rust)
    } else if path_to_module.is_dir()
        && path_to_module
            .read_dir()
            .map_err(|e| anyhow::anyhow!("Failed to read directory {}: {}", path_to_module.display(), e))?
            .flatten()
            .any(|entry| entry.path().extension() == Some("csproj".as_ref()))
    {
        Ok(ModuleLanguage::Csharp)
    } else if path_to_module.join("package.json").exists() {
        Ok(ModuleLanguage::Javascript)
    } else if path_to_module.join("CMakeLists.txt").exists() {
        Ok(ModuleLanguage::Cpp)
    } else {
        anyhow::bail!("Could not detect the language of the module. Are you in a SpacetimeDB project directory?")
    }
}

pub fn url_to_host_and_protocol(url: &str) -> anyhow::Result<(&str, &str)> {
    if contains_protocol(url) {
        let protocol = url.split("://").next().unwrap();
        let host = url.split("://").last().unwrap();

        if !VALID_PROTOCOLS.contains(&protocol) {
            Err(anyhow::anyhow!("Invalid protocol: {protocol}"))
        } else {
            Ok((host, protocol))
        }
    } else {
        Err(anyhow::anyhow!("Invalid url: {url}"))
    }
}

View on GitHub (pinned to 524b4487d9)

Solutions

1. Point the CLI at the directory that actually contains Cargo.toml, package.json, or a .csproj: `spacetime build --module-path ./module-crate`.
2. Scaffold a new module: `spacetime init --lang <rust|csharp|typescript|cpp> <path>`.
3. If submodules are missing: `git submodule update --init --recursive`.
4. If the module is in an unsupported language, rewrite it in a supported one.

Example fix

# before — run from repo root, no manifest visible
spacetime build
# after — point at the crate that contains Cargo.toml
spacetime build --module-path ./module-server

fn is_supported_module(dir: &std::path::Path) -> bool {
    if dir.join("Cargo.toml").exists() || dir.join("package.json").exists() || dir.join("CMakeLists.txt").exists() {
        return true;
    }
    std::fs::read_dir(dir).map(|rd| rd.flatten().any(|e| e.path().extension().is_some_and(|x| x == "csproj"))).unwrap_or(false)
}
// call before invoking the CLI
assert!(is_supported_module(path.as_ref()), "no Rust/C#/JS/C++ manifest in {}", path.display());

When it happens

Trigger: Running spacetime build/publish inside a plain directory or fresh git repo that has no module scaffold; pointing --module-path at the repo root when the module is nested deeper; a module written in a language SpacetimeDB does not support; an empty directory after a partial clone or missing git submodules.

Common situations: Forgot to run `spacetime init`; cloned a project without initializing submodules; renamed or moved the module crate so its manifest file is no longer in the expected directory.

Related errors

• Could not find a SpacetimeDB module in spacetimedb/ or the c
• Fatal Error: path {} exists but is not a directory.
• Fatal Error: path {} does not exist.
• Not in a SpacetimeDB project directory
• Module directory does not exist: '{}'. Check your --module-p

AI-assisted analysis of clockworklabs/SpacetimeDB@524b4487d9 (2026-08-16). Data as JSON: /api/errors/22cf0e49ffa26f26. Report an issue: GitHub.