BerriAI/litellm · error · ValueError

image_response must be of type ImageResponse, got type={type

Error message

image_response must be of type ImageResponse, got type={type(image_response)}

What it means

Type guard in the RunwayML cost calculator: pricing is per generated image, but the object passed as image_response is not an ImageResponse instance (wrong shape from a nonstandard handler), so num_images cannot be determined.

Source

Thrown at litellm/llms/runwayml/cost_calculator.py:28

) -> float:
    """
    RunwayML image generation cost calculator.

    RunwayML charges per image generated, not per pixel.
    Pricing is stored in model_prices_and_context_window.json with output_cost_per_image.
    """
    _model_info: Final = litellm.get_model_info(
        model=model,
        custom_llm_provider=litellm.LlmProviders.RUNWAYML.value,
    )
    output_cost_per_image: Final[float] = _model_info.get("output_cost_per_image") or 0.0
    num_images: int = 0
    if isinstance(image_response, ImageResponse):
        if image_response.data:
            num_images = len(image_response.data)
        return output_cost_per_image * num_images
    else:
        raise ValueError(f"image_response must be of type ImageResponse, got type={type(image_response)}")

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Internal type check failed; pass the ImageResponse returned by litellm rather than a custom object.
2. If reached from a public call, report it to the litellm issue tracker.

Example fix

# use litellm.image_generation output directly for cost tracking.

When it happens

Trigger: Triggered when the RunwayML cost calculator receives an image_response that is not an ImageResponse instance.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/4dcf6ebadcb651ac. Report an issue: GitHub.