{"record":{"id":"4d97fc12076b6b1d","repo":"langchain-ai/langgraph","slug":"remapping-for-fields-starting-with-or-fields-w","errorCode":null,"errorMessage":"Remapping for fields starting with '_' or fields with a name matching a reserved name {_RESERVED_NAMES} is not supported if  the field is a pydantic Field instance. Got {key}.","messagePattern":"Remapping for fields starting with '_' or fields with a name matching a reserved name (.+?) is not supported if  the field is a pydantic Field instance\\. Got (.+?)\\.","errorType":"validation","errorClass":"NotImplementedError","httpStatus":null,"severity":"error","filePath":"libs/langgraph/langgraph/_internal/_pydantic.py","lineNumber":165,"sourceCode":"# \"model_post_init\", \"model_rebuild\", \"model_validate\", \"model_validate_json\",\n# \"model_validate_strings\"\n_RESERVED_NAMES = {key for key in dir(BaseModel) if not key.startswith(\"_\")}\n\n\ndef _remap_field_definitions(field_definitions: dict[str, Any]) -> dict[str, Any]:\n    \"\"\"This remaps fields to avoid colliding with internal pydantic fields.\"\"\"\n\n    remapped = {}\n    for key, value in field_definitions.items():\n        if key.startswith(\"_\") or key in _RESERVED_NAMES:\n            # Let's add a prefix to avoid colliding with internal pydantic fields\n            if isinstance(value, FieldInfo):\n                msg = (\n                    f\"Remapping for fields starting with '_' or fields with a name \"\n                    f\"matching a reserved name {_RESERVED_NAMES} is not supported if \"\n                    f\" the field is a pydantic Field instance. Got {key}.\"\n                )\n                raise NotImplementedError(msg)\n            type_, default_ = value\n            remapped[f\"private_{key}\"] = (\n                type_,\n                Field(\n                    default=default_,\n                    alias=key,\n                    serialization_alias=key,\n                    title=key.lstrip(\"_\").replace(\"_\", \" \").title(),\n                ),\n            )\n        else:\n            remapped[key] = value\n    return remapped\n\n\ndef create_model(\n    model_name: str,\n    *,","sourceCodeStart":147,"sourceCodeEnd":183,"githubUrl":"https://github.com/langchain-ai/langgraph/blob/38031739e551638e373fb553453256c23feeb41f/libs/langgraph/langgraph/_internal/_pydantic.py#L147-L183","documentation":"Error \"Remapping for fields starting with '_' or fields with a name matching a reserved name {_RESERVED_NAMES} is not supported if  the field is a pydantic Field instance. Got {key}.\" thrown in langchain-ai/langgraph.","triggerScenarios":"Thrown at libs/langgraph/langgraph/_internal/_pydantic.py:165 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"}