What causes "ChatGPT Codex generation failed{f' ({code})' if code else ''}." in unslothai/unsloth?

Inspect the (code) in the message to route: server_error → retry with backoff; content policy → adjust prompt; rate_limit → back off

unslothai/unsloth · error · CodexTransportError

ChatGPT Codex generation failed{f' ({code})' if code else ''

Error message

ChatGPT Codex generation failed{f' ({code})' if code else ''}.

What it means

The SSE stream delivered a terminal 'response.failed' or 'error' event: ChatGPT accepted the request but the generation itself failed server-side. The error code extracted from event.error.code (or response.error.code) is embedded in the message, e.g. 'ChatGPT Codex generation failed (server_error)'.

Source

Thrown at studio/backend/core/inference/openai_codex_client.py:710

                                else ("tool_calls" if saw_tool_call else "stop")
                            )
                            yield _chunk(
                                completion_id,
                                model,
                                delta,
                                finish,
                                responses_usage_to_chat(response_body.get("usage")),
                            )
                            emitted_terminal = True
                            break
                        elif kind in ("response.failed", "error"):
                            error = (
                                event.get("error")
                                or (event.get("response") or {}).get("error")
                                or {}
                            )
                            code = error.get("code") if isinstance(error, dict) else None
                            raise CodexTransportError(
                                f"ChatGPT Codex generation failed{f' ({code})' if code else ''}."
                            )
                except httpx.HTTPError:
                    if cancel_event is not None and cancel_event.is_set():
                        return
                    raise
        finally:
            if cancel_task is not None:
                cancel_task.cancel()
        if not emitted_terminal and not (cancel_event is not None and cancel_event.is_set()):
            raise CodexTransportError("ChatGPT stream ended before completion.")

View on GitHub (pinned to 203007d190)

Solutions

Inspect the (code) in the message to route: server_error → retry with backoff; content policy → adjust prompt; rate_limit → back off
Retry once for transient codes before surfacing to the user
Reduce max output tokens or split the task if failures cluster on long generations

Defensive patterns

Strategy: try-catch

Try / catch

try:
    collect(stream)
except CodexTransportError as exc:
    if 'generation failed' not in str(exc):
        raise
    code = parse_failure_code(str(exc))
    if code in ('server_error', 'rate_limit'):
        return await retry_with_backoff(request)
    surface_policy_or_permanent_error(code)

Prevention

Map failure codes to policies: retry transient codes, block prompts that trip content policy
Cap max output tokens to reduce exposure to mid-generation failures
Keep partial output only for display, never treat it as a completed generation

When it happens

Trigger: Streaming a generation that dies mid-completion; the endpoint emits event: response.failed or a top-level error event. Code values identify the cause (server_error, content_policy_violation, rate_limit, etc.).

Common situations: Prompt or output tripping content policy; upstream capacity errors during peak load; overly long generations hitting server limits; tool-heavy requests failing on the server.

Related errors

AI-assisted analysis of unslothai/unsloth@203007d190 (2026-08-15). Data as JSON: /api/errors/5fa6eef7a60ffaa3. Report an issue: GitHub.