BerriAI/litellm · error · ValueError

unknown mapper name {name!r}; known: {known}

Error message

unknown mapper name {name!r}; known: {known}

What it means

Error "unknown mapper name {name!r}; known: {known}" thrown in BerriAI/litellm.

Source

Thrown at litellm/integrations/otel/mappers/__init__.py:47

_TOOL_DEFINITION_MAPPERS: Final[dict[str, Callable[[int], AttributeMapper]]] = {
    "genai": GenAIMapper,
    "legacy": LegacyMapper,
    "openinference": OpenInferenceMapper,
}
_PLAIN_MAPPERS: Final[dict[str, Callable[[], AttributeMapper]]] = {
    "langfuse": LangfuseMapper,
    "weave": WeaveMapper,
    "langtrace": LangtraceMapper,
}


def resolve_mappers(names: Iterable[str]) -> list[AttributeMapper]:
    """Resolve mapper names to instances. Unknown names raise ``ValueError``."""
    ordered: Final = tuple(names)
    for name in ordered:
        if name not in _TOOL_DEFINITION_MAPPERS and name not in _PLAIN_MAPPERS:
            known = sorted((*_TOOL_DEFINITION_MAPPERS, *_PLAIN_MAPPERS))
            raise ValueError(f"unknown mapper name {name!r}; known: {known}")
    # Distinct vocabularies each write the tool family under their own keys, so
    # the ceiling is split by how many of them are configured. Repeating a name
    # rewrites the same keys, so only distinct ones count.
    budget: Final = tool_attr_budget(len({*ordered} & _TOOL_DEFINITION_MAPPERS.keys()))
    return [
        _TOOL_DEFINITION_MAPPERS[name](budget) if name in _TOOL_DEFINITION_MAPPERS else _PLAIN_MAPPERS[name]()
        for name in ordered
    ]


__all__ = [
    "AttrValue",
    "AttributeMap",
    "AttributeMapper",
    "GenAIMapper",
    "LangfuseMapper",
    "LangtraceMapper",
    "LegacyMapper",

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Use one of the known mapper names listed in the error.

When it happens

Trigger: Thrown at litellm/integrations/otel/mappers/__init__.py:47 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/ac598a45047aa82a. Report an issue: GitHub.