langchain-ai/deepagents · error · FileNotFoundError

Plugin source directory not found: {source}

Error message

Plugin source directory not found: {source}

What it means

FileNotFoundError raised by cache_and_register_plugin when the directory given as `source_dir` does not resolve to an existing directory on disk. The plugin must be copied from this source into the versioned plugin cache before registration, so a missing source is fatal.

Source

Thrown at libs/code/deepagents_code/plugins/store.py:510

    """Copy a plugin into the versioned cache and register the install.

    Args:
        plugin_id: Plugin id in `{name}@{marketplace}` form.
        source_dir: Source plugin root to copy from.
        version: Version declared by the plugin manifest, if any.
        validate: Optional validation to run before registering the cache.

    Returns:
        Absolute path to the cached plugin root.

    Raises:
        FileNotFoundError: If `source_dir` is not an existing directory.
        OSError: If the cache cannot be copied or atomically replaced.
    """
    source = source_dir.resolve()
    if not source.is_dir():
        msg = f"Plugin source directory not found: {source}"
        raise FileNotFoundError(msg)

    cache_path = versioned_cache_path(plugin_id, version)
    if cache_path.exists() and version is not None:
        try:
            if any(cache_path.iterdir()):
                if validate is not None:
                    validate(cache_path)
                add_installed_plugin(
                    plugin_id,
                    install_path=str(cache_path),
                    version=version,
                )
                return cache_path
        except OSError:
            pass

    cache_path.parent.mkdir(parents=True, exist_ok=True)
    temp_dir = cache_path.parent / f".{cache_path.name}.tmp-{os.getpid()}"

View on GitHub (pinned to a1af029e6e)

Solutions

1. Verify the path exists and is a directory: ls <source_dir>
2. Rebuild or re-clone the plugin source before installing
3. Pass an absolute path to avoid resolution surprises from the current working directory
4. If the plugin ships via marketplace, install by id instead of a local source path

Example fix

// before
await install_plugin(plugin_id="my-plugin", source_dir="./plugn")  # typo

// after
await install_plugin(plugin_id="my-plugin", source_dir="/abs/path/to/my-plugin")

from pathlib import Path
source = Path(source_dir).resolve()
if not source.is_dir():
    raise FileNotFoundError(f"plugin source is not a directory: {source}")

try:
    await install_plugin(plugin_id=p, source_dir=src)
except FileNotFoundError:
    console.print(f"[red]Source {src} missing — rebuild the plugin first.[/red]")

When it happens

Trigger: Calling install_plugin or auto_update_plugins with a `source_dir` that has been deleted, moved, was never created, or is a file rather than a directory; `source_dir.resolve()` + `is_dir()` fails before any caching begins.

Common situations: Typo in the local plugin path; building the plugin in a temp dir that was cleaned up; pointing install at a git repo root whose checkout was removed; relative path resolved from an unexpected working directory.

Related errors

• Could not find {target_name} inside {archive.name}
• Installed {plugin_id} but failed to load from cache: {detail
• Could not read plugin manifest {manifest_path}: {exc}
• Path does not exist: {path}
• Marketplace URL {_redact_url_credentials(url)} only download

AI-assisted analysis of langchain-ai/deepagents@a1af029e6e (2026-08-29). Data as JSON: /api/errors/8637e8ca45133811. Report an issue: GitHub.