> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apiyi.com/llms.txt
> Use this file to discover all available pages before exploring further.

# FAQ: reasoning models returning empty content

> On reasoning models, the thinking trace can consume the whole max_tokens budget, leaving no visible output and triggering empty_response. The new FAQ explains three checks and three fixes.

**2026/11/8 21:50 (UTC+8)** · Docs Update · OpenAI

📖 **New FAQ: why does a reasoning model return empty content?**

On reasoning models such as `gpt-6.1-sol`, the thinking trace and the visible answer share the same `max_tokens` budget. When the budget is small (300, for example), the model may spend all of it on thinking and get cut off before writing the answer, so the API returns `empty_response` or an HTTP 200 with an empty `message.content`.

The new page walks through three checks (`finish_reason`, `reasoning_tokens`, `max_tokens`) and three fixes (raise `max_tokens`, lower `reasoning_effort`, switch to streaming), and explains how these requests are billed.

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