langchain-ai/langgraph · error · ValueError

Graph '{graph_id}' must be a string or a dictionary with a '

Error message

Graph '{graph_id}' must be a string or a dictionary with a 'path' key.

What it means

Error "Graph '{graph_id}' must be a string or a dictionary with a 'path' key." thrown in langchain-ai/langgraph.

Source

Thrown at libs/cli/langgraph_cli/config.py:878

    Raises:
        ValueError: If the import string is not in the format `<module>:<attribute>`
                    or if the referenced local file is not found in `dependencies`.
        FileNotFoundError: If the local file (module) does not actually exist on disk.
        IsADirectoryError: If `module_str` points to a directory instead of a file.
    """
    for graph_id, data in config["graphs"].items():
        if isinstance(data, dict):
            # Then we're looking for a 'path' key
            if "path" not in data:
                raise ValueError(
                    f"Graph '{graph_id}' must contain a 'path' key if "
                    f" it is a dictionary."
                )
            import_str = data["path"]
        elif isinstance(data, str):
            import_str = data
        else:
            raise ValueError(
                f"Graph '{graph_id}' must be a string or a dictionary with a 'path' key."
            )

        module_str, _, attr_str = import_str.partition(":")
        if not module_str or not attr_str:
            message = (
                'Import string "{import_str}" must be in format "<module>:<attribute>".'
            )
            raise ValueError(message.format(import_str=import_str))

        # Check for either forward slash or backslash in the module string
        # to determine if it's a file path.
        if "/" in module_str or "\\" in module_str:
            # Resolve the local path properly on the current OS
            resolved = (config_path.parent / module_str).resolve()
            if not resolved.exists():
                raise FileNotFoundError(f"Could not find local module: {resolved}")
            elif not resolved.is_file():

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/cli/langgraph_cli/config.py:878 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/c18d72fbf7683d65. Report an issue: GitHub.