Item 'rs...' of type 'reasoning' was provided without its required following item.

May have discovered a workaround:

model_reasoning_effort = "none"

Explicitly setting this to none seems to work. This might have to do with incompatibilties on Azure's end. A conversation with ChatGPT revealed this so take this with a grain of salt (or an entire salt shaker's worth). I haven't had time to look into this more but I've got codex working now:

From ChatGPT

1. \\Codex 0.4–0.5 automatically requests a \\*reasoning trace* for every o‑series / codex‑series model (unless you override it). That makes the model stream events whose type is reasoning.
2. Azure’s Responses endpoint requires you to send that trace back on the next request, either as previous_response_id or by echoing reasoning.encrypted_content.
3. Codex‑RS doesn’t yet forward either field, so Azure rejects the request with the 400 above. (Is this true?)

---

model_reasoning_effort            = "none"

This tells Codex not to request the extra channel, so no dangling rs_… ID is produced and Azure is satisfied. You lose only the verbose chain‑of‑thought payload—not the model’s actual reasoning ability.

---

References

1. Encrypted Reasoning Items, Azure OpenAI Responses API (Preview) — Microsoft Learn  https://learn.microsoft.com/en-us/azure/ai-foundry/openai/how-to/responses#encrypted-reasoning-items
2. Reasoning models guide, Azure OpenAI — Microsoft Learn  https://learn.microsoft.com/en-us/azure/ai-foundry/openai/how-to/reasoning#reasoning-effort

I have the same error using the official openai package in my app. your workaround fixed it. There are multiple threads on platform.openai.com
How to solve “BadRequestError: 400 Item ‘rs_ … ’ of type ‘reasoning’ was provided without its required following item” error in Responses API
Responses API: invalid_request_error - ‘function_call’ was provided without its required ‘reasoning’ item

@kingdomseed, thanks for filing the bug report. Apologies for the slow reply — we got far behind on our issues.

Are you still seeing this problem? I'm guessing that it's no longer relevant, since much has changed in the CLI since you originally filed it.

I'm going to mark the issue as closed. If you are still seeing the problem, let us know, and I'll reopen.

{"latest_version":"0.52.0","last_checked_at":"2025-10-30T20:39:31.893083Z","dismissed_version":null}

Seeing constant interruptions, it starts doing something but next input breaks it with

■ unexpected status 400 Bad Request: {
  "error": {
    "message": "Item 'fc_xxx' of type 'function_call' was provided without its required
'reasoning' item: 'rs_xxx'.",
    "type": "invalid_request_error",
    "param": "input",
    "code": null
  }
}

Config

[model_providers.azure]
api_version = "2025-04-01-preview"
base_url = "https://codex-resource.openai.azure.com/openai/v1"
deployment = "gpt-5-codex"
env_key = "AZURE_OPENAI_API_KEY"
model = "gpt-5-codex"
model_reasoning_effort = "none"
name = "Azure OpenAI"
wire_api = "responses"

@OperationalFallacy, thanks for reporting. Others are reporting the same problem with 0.52.0 in this bug report. Let's use that one to track the issue.