BerriAI/litellm · error · ValueError

Either 'model' or 'agent' must be provided

Error message

Either 'model' or 'agent' must be provided

What it means

Error "Either 'model' or 'agent' must be provided" thrown in BerriAI/litellm.

Source

Thrown at litellm/llms/gemini/interactions/transformation.py:154

        - ``response_mime_type`` is folded into ``response_format`` and stripped from
          the body (the field was removed in Api-Revision 2026-05-20).
        - ``generation_config.image_config`` is moved to a ``response_format`` entry
          with ``"type": "image"`` (also removed from generation_config in 2026-05-20).

        When on the legacy schema (use_legacy_interactions_schema=True):
        - All fields are forwarded as-is.
        """
        use_legacy: Final[bool] = litellm.use_legacy_interactions_schema

        request_body: Final[dict[str, Any]] = {}

        # Model or Agent (one required)
        if model:
            request_body["model"] = GeminiModelInfo.get_base_model(model) or model
        elif agent:
            request_body["agent"] = agent
        else:
            raise ValueError("Either 'model' or 'agent' must be provided")

        # Input
        if input is not None:
            request_body["input"] = input

        # Pass through optional params — legacy schema keeps all fields as-is.
        optional_keys: Final = [
            "tools",
            "system_instruction",
            "stream",
            "store",
            "background",
            "environment",
            "response_modalities",
            "previous_interaction_id",
        ]
        for key in optional_keys:
            if optional_params.get(key) is not None:

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Pass either model or agent in the interactions request.

When it happens

Trigger: Thrown at litellm/llms/gemini/interactions/transformation.py:154 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/07a3759fb385f20a. Report an issue: GitHub.