Responses API error with "type reasoning provided without its required following item"

API Bugs
1

Most of the time function calls with o4-mini and the responses API works great. Occasionally, I get the following error:

“Item ‘rs_684308adb3c4819bba96ef6883a4d9e7059dff5718d7b7a6’ of type ‘reasoning’ was provided without its required following item.”

After being very confused, I looked at the logs in the OpenAI dashboard. Everything looks correct at first glance, but looking at the network requests I see this in the details:

  "max_output_tokens": null,
  "model": "o4-mini-2025-04-16",
  "next_response_ids": [],
  "output": [
    {
      "id": "rs_684308adb3c4819bba96ef6883a4d9e7059dff5718d7b7a6",
      "type": "reasoning",
      "summary": []
    },
    {
      "id": "rs_684308b5cf04819bac3741bf179c1bce059dff5718d7b7a6",
      "type": "reasoning",
      "summary": []
    },
    {
      "id": "fc_684308b60908819b9cd091c4603191f6059dff5718d7b7a6",
      "type": "function_call",
      "status": "completed",
// redacted
    }
  ],

It really looks like the Responses API thinks that there are two reasoning outputs in a row. I only see this on the logs that are breaking.

I don’t think this is related to the client code at all. I don’t even know how I would be able to add or remove those outputs to “fix” the problem. I think it needs to be fixed on the OpenAI api server.

2

I’ve seen ChatGPT produce multiple “thought for 15 seconds”, “thought for 10 seconds” in a row, restarting its output or message to be so detected in the UI before any user response.

Perhaps the Responses API doesn’t anticipate this behavior and doesn’t assign unique IDs, but only one ID generated per response. Then you get an error in sending them back.

There is at least one more report of this I’ve seen on the forum to be searched, with the symptom.

I would make a record of the response ID (or multiple) where you can replicate this again making the chat unable to be continued on, and make a high-quality bug report here and mirror it to support@openai.com.

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