{"record":{"id":"3c6cc7dcfd8a9502","repo":"hiyouga/LlamaFactory","slug":"dataset-converter-name-not-found","errorCode":null,"errorMessage":"Dataset converter {name} not found.","messagePattern":"Dataset converter (.+?) not found\\.","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"src/llamafactory/data/converter.py","lineNumber":388,"sourceCode":"DATASET_CONVERTERS = {\n    \"alpaca\": AlpacaDatasetConverter,\n    \"sharegpt\": SharegptDatasetConverter,\n    \"openai\": OpenAIDatasetConverter,\n}\n\n\ndef register_dataset_converter(name: str, dataset_converter: type[\"DatasetConverter\"]) -> None:\n    r\"\"\"Register a new dataset converter.\"\"\"\n    if name in DATASET_CONVERTERS:\n        raise ValueError(f\"Dataset converter {name} already exists.\")\n\n    DATASET_CONVERTERS[name] = dataset_converter\n\n\ndef get_dataset_converter(name: str, dataset_attr: \"DatasetAttr\", data_args: \"DataArguments\") -> \"DatasetConverter\":\n    r\"\"\"Get a dataset converter.\"\"\"\n    if name not in DATASET_CONVERTERS:\n        raise ValueError(f\"Dataset converter {name} not found.\")\n\n    return DATASET_CONVERTERS[name](dataset_attr, data_args)\n\n\ndef align_dataset(\n    dataset: Union[\"Dataset\", \"IterableDataset\"],\n    dataset_attr: \"DatasetAttr\",\n    data_args: \"DataArguments\",\n    training_args: \"Seq2SeqTrainingArguments\",\n) -> Union[\"Dataset\", \"IterableDataset\"]:\n    r\"\"\"Align the dataset to a specific format.\n\n    Aligned dataset:\n    _prompt: [{\"role\": \"user\", \"content\": \"...\"}] * (2T - 1)\n    _response: [{\"role\": \"assistant\", \"content\": \"...\"}] * N (N > 1 for ranking dataset)\n    _system: \"...\"\n    _tools: \"...\"\n    _images: []","sourceCodeStart":370,"sourceCodeEnd":406,"githubUrl":"https://github.com/hiyouga/LlamaFactory/blob/f28afaf6355af515454dfb16c97d728307c93897/src/llamafactory/data/converter.py#L370-L406","documentation":"get_dataset_converter raises ValueError when the requested format name is not a key of DATASET_CONVERTERS (only 'alpaca', 'sharegpt', 'openai' ship built in, plus whatever plugins registered). The name comes from dataset_attr.formatting, i.e. the 'formatting' field of a dataset_info.json entry.","triggerScenarios":"A dataset_info.json entry with formatting: \"chatml\" (or any unregistered name) passed to align_dataset/get_converter; a typo like 'sharegpt ' or 'OpenAI'; relying on a plugin converter that was never imported in the current process.","commonSituations":"Hand-written dataset_info.json entries; plugin converters that require an explicit import of the plugin module; upgrading LlamaFactory and assuming a removed/renamed formatting value still exists.","solutions":["Set formatting to one of alpaca | sharegpt | openai in the dataset_info entry, matching your data schema.","Fix typos/whitespace/case in the formatting field.","If you use a custom converter, ensure its registration module is imported before dataset loading (e.g. via your entrypoint)."],"exampleFix":"# before (dataset_info.json)\n\"my_data\": {\"file_name\": \"data.json\", \"formatting\": \"chatml\"}\n\n# after (dataset_info.json)\n\"my_data\": {\"file_name\": \"data.json\", \"formatting\": \"sharegpt\", \"formatting_sharegpt\": {\"tags\": {\"role_tag\": \"role\", \"content_tag\": \"content\", \"user_tag\": \"user\", \"assistant_tag\": \"assistant\"}}}","handlingStrategy":"validation","validationCode":"from llamafactory.data.converter import DATASET_CONVERTERS\nfmt = dataset_attr.formatting\nif fmt not in DATASET_CONVERTERS:\n    raise ValueError(f\"formatting '{fmt}' invalid; choose from {sorted(DATASET_CONVERTERS)}\")","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Validate dataset_info.json entries against the converter registry before launching training.","Prefer built-in formatting names unless a plugin is deliberately imported."],"tags":["dataset","converter","registry","config"],"backgroundTag":null,"analyzedSha":"f28afaf6355af515454dfb16c97d728307c93897","analyzedAt":"2026-08-14T21:57:28.298Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}