run-llama/llama_index · error · ValueError

Parser loading requires a class_name

Error message

Parser loading requires a class_name

What it means

Error "Parser loading requires a class_name" thrown in run-llama/llama_index.

Source

Thrown at llama-index-core/llama_index/core/node_parser/loading.py:38

    JSONNodeParser.class_name(): JSONNodeParser,
    MarkdownNodeParser.class_name(): MarkdownNodeParser,
    SimpleFileNodeParser.class_name(): SimpleFileNodeParser,
    HierarchicalNodeParser.class_name(): HierarchicalNodeParser,
    CodeSplitter.class_name(): CodeSplitter,
    SentenceSplitter.class_name(): SentenceSplitter,
    TokenTextSplitter.class_name(): TokenTextSplitter,
    SentenceWindowNodeParser.class_name(): SentenceWindowNodeParser,
}


def load_parser(
    data: dict,
) -> NodeParser:
    if isinstance(data, NodeParser):
        return data
    parser_name = data.get("class_name")
    if parser_name is None:
        raise ValueError("Parser loading requires a class_name")

    if parser_name not in all_node_parsers:
        raise ValueError(f"Invalid parser name: {parser_name}")
    else:
        return all_node_parsers[parser_name].from_dict(data)

View on GitHub (pinned to afd0fef371)

Solutions

1. Include class_name in the serialized parser data.
2. Re-serialize the parser with its class name before loading.

When it happens

Trigger: Thrown at llama-index-core/llama_index/core/node_parser/loading.py:38 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of run-llama/llama_index@afd0fef371 (2026-08-15). Data as JSON: /api/errors/99ebc73cfc666d16. Report an issue: GitHub.