BerriAI/litellm · error · OpenRouterException

KeyError: {e}, Got unexpected response from OpenRouter: {chu

Error message

KeyError: {e}, Got unexpected response from OpenRouter: {chunk}

What it means

The streaming chunk from OpenRouter lacks expected keys (choices/delta/id), so chunk parsing raised KeyError; the raw chunk is embedded in the error because the response deviates from the documented streaming schema.

Source

Thrown at litellm/llms/openrouter/chat/transformation.py:282

                    message=error_message["message"],
                    status_code=error_message["code"],
                    headers=error_message["metadata"].get("headers", {}),
                )

            new_choices: Final = []
            for choice in chunk["choices"]:
                choice["delta"]["reasoning_content"] = choice["delta"].get("reasoning")
                new_choices.append(choice)
            return ModelResponseStream(
                id=chunk["id"],
                object="chat.completion.chunk",
                created=chunk["created"],
                usage=chunk.get("usage"),
                model=chunk["model"],
                choices=new_choices,
            )
        except KeyError as e:
            raise OpenRouterException(
                message=f"KeyError: {e}, Got unexpected response from OpenRouter: {chunk}",
                status_code=400,
                headers={"Content-Type": "application/json"},
            )
        except Exception as e:
            raise e

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Inspect the unexpected OpenRouter chunk in the message; retry and, if persistent, check OpenRouter status or adjust the model.

When it happens

Trigger: Thrown at litellm/llms/openrouter/chat/transformation.py:282 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/5bb3061f989befea. Report an issue: GitHub.