langchain-ai/langgraph · error · IsADirectoryError

Auth path must be a file

Error message

Auth path must be a file: {resolved}

What it means

Raised during langgraph.json config preparation when the auth.path entry uses the relative 'module:attribute' form but the resolved file (config directory joined with the module path) does not exist on disk. It is a config-validation failure: the file pointing to your auth implementation is missing or misnamed, not a runtime auth error. Fix the path in langgraph.json or create the referenced file.

Solutions

1. Point auth.path at the specific .py file, e.g. './auth.py:auth'.
2. Include the ':<attribute>' suffix.

When it happens

Trigger: Thrown at libs/cli/langgraph_cli/config.py:943 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of langchain-ai/langgraph@38031739e5 (2026-08-26). Data as JSON: /api/errors/4d2f396537ca6062. Report an issue: GitHub.

Appendix: source

Thrown at libs/cli/langgraph_cli/config.py:943

def _update_auth_path(
    config_path: pathlib.Path, config: Config, local_deps: LocalDeps
) -> None:
    """Update auth.path to use Docker container paths."""
    auth_conf = config.get("auth")
    if not auth_conf or not (path_str := auth_conf.get("path")):
        return

    module_str, sep, attr_str = path_str.partition(":")
    if not sep or not module_str.startswith("."):
        return  # Already validated or absolute path

    resolved = config_path.parent / module_str
    if not resolved.exists():
        raise FileNotFoundError(f"Auth file not found: {resolved} (from {path_str})")
    if not resolved.is_file():
        raise IsADirectoryError(f"Auth path must be a file: {resolved}")

    # Check faux packages first (higher priority)
    for faux_path, (_, destpath) in local_deps.faux_pkgs.items():
        if resolved.is_relative_to(faux_path):
            new_path = f"{destpath}/{resolved.relative_to(faux_path)}:{attr_str}"
            auth_conf["path"] = new_path
            return

    # Check real packages
    for real_path in local_deps.real_pkgs:
        if resolved.is_relative_to(real_path):
            new_path = (
                f"/deps/{real_path.name}/{resolved.relative_to(real_path)}:{attr_str}"
            )
            auth_conf["path"] = new_path
            return

    raise ValueError(

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