BerriAI/litellm · error · UnsupportedParamsError

Azure does not support 'tool_choice', for api_version={api_v

Error message

Azure does not support 'tool_choice', for api_version={api_version}. Bump your API version to '2023-12-01-preview' or later. This parameter requires 'api_version="2023-12-01-preview"' or later. Azure API Reference: https://learn.microsoft.com/en-us/azure/ai-services/openai/reference#chat-completions

What it means

Error "Azure does not support 'tool_choice', for api_version={api_version}. Bump your API version to '2023-12-01-preview' or later. This parameter requires 'api_version="2023-12-01-preview"' or later. Azure API Reference: https://learn.microsoft.com/en-us/azure/ai-services/openai/reference#chat-completions" thrown in BerriAI/litellm.

Source

Thrown at litellm/llms/azure/chat/gpt_transformation.py:193

            if param == "tool_choice":
                """
                This parameter requires API version 2023-12-01-preview or later

                tool_choice='required' is not supported as of 2024-05-01-preview
                """
                ## check if api version supports this param ##
                if api_version_year is None or api_version_month is None or api_version_day is None:
                    optional_params["tool_choice"] = value
                else:
                    if (
                        api_version_year < "2023"
                        or (api_version_year == "2023" and api_version_month < "12")
                        or (api_version_year == "2023" and api_version_month == "12" and api_version_day < "01")
                    ):
                        if litellm.drop_params is True or (drop_params is not None and drop_params is True):
                            pass
                        else:
                            raise UnsupportedParamsError(
                                status_code=400,
                                message=f"""Azure does not support 'tool_choice', for api_version={api_version}. Bump your API version to '2023-12-01-preview' or later. This parameter requires 'api_version="2023-12-01-preview"' or later. Azure API Reference: https://learn.microsoft.com/en-us/azure/ai-services/openai/reference#chat-completions""",
                            )
                    elif value == "required" and (
                        api_version_year == "2024" and api_version_month <= "05"
                    ):  ## check if tool_choice value is supported ##
                        if litellm.drop_params is True or (drop_params is not None and drop_params is True):
                            pass
                        else:
                            raise UnsupportedParamsError(
                                status_code=400,
                                message=f"Azure does not support '{value}' as a {param} param, for api_version={api_version}. To drop 'tool_choice=required' for calls with this Azure API version, set `litellm.drop_params=True` or for proxy:\n\n`litellm_settings:\n drop_params: true`\nAzure API Reference: https://learn.microsoft.com/en-us/azure/ai-services/openai/reference#chat-completions",
                            )
                    else:
                        optional_params["tool_choice"] = value
            elif param == "response_format" and isinstance(value, dict):
                _is_response_format_supported_model = self._is_response_format_supported_model(model)

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Bump api_version to 2023-12-01-preview or later to use tool_choice.

When it happens

Trigger: Thrown at litellm/llms/azure/chat/gpt_transformation.py:193 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/6ae5f7a9f2181125. Report an issue: GitHub.