BerriAI/litellm · error · ValueError

RunwayML TTS response missing audio URL in output

Error message

RunwayML TTS response missing audio URL in output

What it means

Contract guard after RunwayML TTS polling completes: the finished task's 'output' field is empty or not a non-empty list, so there is no audio URL to download; raised instead of returning an empty audio result.

Source

Thrown at litellm/llms/runwayml/text_to_speech/transformation.py:493

        }

        # Poll until task completes
        polled_response: Final = self._poll_task_sync(
            task_id=task_id,
            api_base=self.DEFAULT_BASE_URL,
            headers=poll_headers,
            timeout_secs=RUNWAYML_POLLING_TIMEOUT,
        )

        # Get the completed task data
        task_data: Final = polled_response.json()

        verbose_logger.debug("RunwayML TTS polling complete, downloading audio")

        # Get audio URL from output
        output: Final = task_data.get("output", [])
        if not output or not isinstance(output, list) or len(output) == 0:
            raise ValueError("RunwayML TTS response missing audio URL in output")

        audio_url: Final = output[0]
        if not isinstance(audio_url, str):
            raise ValueError(f"RunwayML TTS audio URL is not a string: {audio_url}")

        # Download the audio file
        from litellm.llms.custom_httpx.http_handler import _get_httpx_client

        client: Final = _get_httpx_client()
        audio_response: Final = client.get(url=audio_url)
        audio_response.raise_for_status()

        verbose_logger.debug("RunwayML TTS audio downloaded successfully")

        # Return the audio data wrapped in HttpxBinaryResponseContent
        return HttpxBinaryResponseContent(audio_response)

    async def async_transform_text_to_speech_response(

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. The completed task output had no audio URL; inspect the task output payload.
2. Report to litellm issue tracker if the RunwayML output schema changed.

Example fix

# fetch the task directly from RunwayML and check its output field.

When it happens

Trigger: Triggered when the RunwayML TTS task output does not contain an audio URL.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/461e7fb4331b3d9b. Report an issue: GitHub.