langchain-ai/langgraph · error · TypeError

Expected a type, got {type(obj)}.

Error message

Expected a type, got {type(obj)}. 

What it means

Error "Expected a type, got {type(obj)}. " thrown in langchain-ai/langgraph.

Source

Thrown at libs/langgraph/langgraph/_internal/_fields.py:213

def get_cached_annotated_keys(obj: type[Any]) -> tuple[str, ...]:
    """Return cached annotated keys for a Python class."""
    if obj in ANNOTATED_KEYS_CACHE:
        return ANNOTATED_KEYS_CACHE[obj]
    if isinstance(obj, type):
        keys: list[str] = []
        for base in reversed(obj.__mro__):
            ann = base.__dict__.get("__annotations__")
            # In Python 3.14+, Pydantic models use descriptors for __annotations__
            # so we need to fall back to getattr if __dict__.get returns None
            if ann is None:
                ann = getattr(base, "__annotations__", None)
            if ann is None or isinstance(ann, types.GetSetDescriptorType):
                continue
            keys.extend(ann.keys())
        return ANNOTATED_KEYS_CACHE.setdefault(obj, tuple(keys))
    else:
        raise TypeError(f"Expected a type, got {type(obj)}. ")

View on GitHub (pinned to 38031739e5)

When it happens

Trigger: Thrown at libs/langgraph/langgraph/_internal/_fields.py:213 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/125e0a6bad8249f8. Report an issue: GitHub.