Getting sporadic invalid URLs using structured outputs API

API Bugs
26

I’m also getting similar errors, but I’m seeing this error for multiple requests. Below is a sample request/response. For this request I’m using Structured Outputs and also linking to a previous_response_id. One of the previous requests in the “same chain of messages” includes images with the prompt.

Request: POST /v1/responses Body:

{
  "model" : "gpt-4.1-mini",
  "temperature" : 0.1,
  "previous_response_id" : "resp_685463d97084819aa8ddb56fe4f562da047c9e6054a143f7",
  "max_output_tokens" : 500,
  "instructions" : "You are an expert at classifying products into which category they fit best. Use the product title, description, features, attributes, and sample images of the product to make your decision. Do not add new special characters. Assign a confidence score between 0-10 on your choice, 10 if you are very confident in your decision and 0 if you are not confident.",
  "input" : [ {
    "role" : "user",
    "content" : [ {
      "type" : "input_text",
      "text" : "For the same product tell me which of the following categories best describes it. Choose from [Toy Action Figures, Action Figure Playsets, Collectible Figures, Animal Figures]"
    } ]
  } ],
  "text" : {
    "format" : {
      "type" : "json_schema",
      "name" : "CategoryResponse",
      "schema" : {
        "type" : "object",
        "properties" : {
          "confidence" : {
            "type" : "integer"
          },
          "choice" : {
            "type" : "string"
          }
        },
        "required" : [ "choice", "confidence" ],
        "additionalProperties" : false
      },
      "strict" : false
    }
  }
}

Response:

Response status: 404 NOT_FOUND Body:
{
  "error": {
    "message": "Invalid URL (POST /v1/engines/gpt-4.1-mini-2025-04-14/completions)",
    "type": "invalid_request_error",
    "param": null,
    "code": null
  }
}
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