openai/codex · error · CodexError

{method} response must be a JSON object

Error message

{method} response must be a JSON object

What it means

Error "{method} response must be a JSON object" thrown in openai/codex.

Source

Thrown at sdk/python/src/openai_codex/client.py:320

                "capabilities": {
                    "experimentalApi": self.config.experimental_api,
                },
            },
            response_model=InitializeResponse,
        )
        self.notify("initialized", None)
        return result

    def request(
        self,
        method: str,
        params: JsonObject | None,
        *,
        response_model: type[ModelT],
    ) -> ModelT:
        result = self._request_raw(method, params)
        if not isinstance(result, dict):
            raise CodexError(f"{method} response must be a JSON object")
        return response_model.model_validate(result)

    def _request_raw(self, method: str, params: JsonObject | None = None) -> JsonValue:
        """Send a JSON-RPC request and wait for the reader thread to route its response."""
        request_id = str(uuid.uuid4())
        waiter = self._router.create_response_waiter(request_id)

        try:
            message: JsonObject = {"id": request_id, "method": method}
            if params is not None:
                message["params"] = params
            self._write_message(message)
        except BaseException:
            self._router.discard_response_waiter(request_id)
            raise

        item = waiter.get()
        if isinstance(item, BaseException):

View on GitHub (pinned to 339751715c)

Solutions

1. Update the SDK and runtime to matching versions so the method returns a JSON object per the protocol.

When it happens

Trigger: Thrown at sdk/python/src/openai_codex/client.py:320 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/79305b0c32b34ed7. Report an issue: GitHub.