{"record":{"id":"ec89b3fe92636a50","repo":"langchain-ai/langgraph","slug":"object-of-type-obj-class-name-is-not-ser","errorCode":null,"errorMessage":"Object of type {obj.__class__.__name__} is not serializable","messagePattern":"Object of type (.+?) is not serializable","errorType":"exception","errorClass":"TypeError","httpStatus":null,"severity":"error","filePath":"libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py","lineNumber":534,"sourceCode":"        obj, np_mod.ndarray\n    ):\n        order = \"F\" if obj.flags.f_contiguous and not obj.flags.c_contiguous else \"C\"\n        if obj.flags.c_contiguous:\n            mv = memoryview(obj)\n            try:\n                meta = (obj.dtype.str, obj.shape, order, mv)\n                return ormsgpack.Ext(EXT_NUMPY_ARRAY, _msgpack_enc(meta))\n            finally:\n                mv.release()\n        else:\n            buf = obj.tobytes(order=\"A\")\n            meta = (obj.dtype.str, obj.shape, order, buf)\n            return ormsgpack.Ext(EXT_NUMPY_ARRAY, _msgpack_enc(meta))\n\n    elif isinstance(obj, BaseException):\n        return repr(obj)\n    else:\n        raise TypeError(f\"Object of type {obj.__class__.__name__} is not serializable\")\n\n\ndef _send_from_args(args: Sequence[Any]) -> Any:\n    # ya we have a cyclic import here ¯\\_(ツ)_/¯\n    from langgraph.types import Send  # type: ignore\n\n    if len(args) == 2:\n        return Send(*args)\n    return Send(args[0], args[1], timeout=args[2])\n\n\ndef _create_msgpack_ext_hook(\n    allowed_modules: set[tuple[str, ...]] | Literal[True] | None,\n) -> Callable[[int, bytes], Any]:\n    \"\"\"Create msgpack ext hook with allowlist.\n\n    Args:\n        allowed_modules: Set of (module, name) tuples that are allowed to be","sourceCodeStart":516,"sourceCodeEnd":552,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py#L516-L552","documentation":"Error \"Object of type {obj.__class__.__name__} is not serializable\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py:534 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"38031739e551638e373fb553453256c23feeb41f","analyzedAt":"2026-08-26T18:02:49.312Z","schemaVersion":2},"datasetVersion":"2026-08-26T21:11:00.512Z"}