BerriAI/litellm · error · ValueError

WatsonX embeddings require a string or list of strings

Error message

WatsonX embeddings require a string or list of strings

What it means

Type guard in the watsonx embedding transform: input is neither a str nor a list of str (it is a list of token-id lists or ints, an OpenAI-style encoding watsonx does not accept), so it cannot be mapped to the watsonx 'inputs' field.

Source

Thrown at litellm/llms/watsonx/embed/transformation.py:50

    def transform_embedding_request(
        self,
        model: str,
        input: AllEmbeddingInputValues,
        optional_params: dict,
        headers: dict,
    ) -> dict:
        watsonx_api_params: Final = _get_api_params(params=optional_params, model=model)
        watsonx_auth_payload: Final = self._prepare_payload(
            model=model,
            api_params=watsonx_api_params,
        )

        if isinstance(input, str):
            inputs: list[str] = [input]
        elif isinstance(input, list):
            if len(input) > 0 and isinstance(input[0], (list, int)):
                raise ValueError("WatsonX embeddings require a string or list of strings")
            inputs = input
        else:
            inputs = [input]

        return {
            "inputs": inputs,
            "parameters": optional_params,
            **watsonx_auth_payload,
        }

    def get_complete_url(
        self,
        api_base: str | None,
        api_key: str | None,
        model: str,
        optional_params: dict,
        litellm_params: dict,
        stream: bool | None = None,

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Pass the embedding input as a string or a list of strings.
2. Convert other input types (dicts, numbers) to strings before calling the Watsonx embedding API.

When it happens

Trigger: Thrown at litellm/llms/watsonx/embed/transformation.py:50 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/95e80e2cd0a1f3c2. Report an issue: GitHub.