{"record":{"id":"055fbd98659436dc","repo":"langchain-ai/langgraph","slug":"when-specifying-root-no-other-fields-should-be","errorCode":null,"errorMessage":"When specifying __root__ no other fields should be provided. Got {field_definitions}","messagePattern":"When specifying __root__ no other fields should be provided\\. Got (.+?)","errorType":"validation","errorClass":"NotImplementedError","httpStatus":null,"severity":"error","filePath":"libs/langgraph/langgraph/_internal/_pydantic.py","lineNumber":211,"sourceCode":"    Args:\n        model_name: The name of the model.\n        module_name: The name of the module where the model is defined.\n            This is used by Pydantic to resolve any forward references.\n        field_definitions: The field definitions for the model.\n        root: Type for a root model (RootModel)\n\n    Returns:\n        Type[BaseModel]: The created model.\n    \"\"\"\n    field_definitions = field_definitions or {}\n\n    if root:\n        if field_definitions:\n            msg = (\n                \"When specifying __root__ no other \"\n                f\"fields should be provided. Got {field_definitions}\"\n            )\n            raise NotImplementedError(msg)\n\n        if isinstance(root, tuple):\n            kwargs = {\"type_\": root[0], \"default_\": root[1]}\n        else:\n            kwargs = {\"type_\": root}\n\n        try:\n            named_root_model = _create_root_model_cached(model_name, **kwargs)\n        except TypeError:\n            # something in the arguments into _create_root_model_cached is not hashable\n            named_root_model = _create_root_model(\n                model_name,\n                **kwargs,\n            )\n        return named_root_model\n\n    # No root, just field definitions\n    names = set(field_definitions.keys())","sourceCodeStart":193,"sourceCodeEnd":229,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/langgraph/langgraph/_internal/_pydantic.py#L193-L229","documentation":"Error \"When specifying __root__ no other fields should be provided. Got {field_definitions}\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/langgraph/langgraph/_internal/_pydantic.py:211 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"}