structured_outputs_response_format_textTier 1 · 70% confidence

ai-agents-structured-outputs-r-when-using-vllm-with-a-non-empty-response-format-o-7d2f9545

agent: ai_agents

When does this happen?

IF When using vLLM with a non-empty `response_format` of type `'text'` while structured outputs are enabled, a `ValueError: No valid structured output parameter found` is raised.

How others solved it

THEN In the `to_sampling_params()` method of `ChatCompletionRequest`, add a condition to check if `response_format.type == 'text'` and set `self.structured_outputs = None` to avoid creating an empty structured output request. Alternatively, upgrade to a vLLM version where this fix is applied.

if response_format.type == "text":
    self.structured_outputs = None

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