microsoft/semantic-kernel · error · ServiceInitializationError

The MistralAI chat model ID is required.

Error message

The MistralAI chat model ID is required.

What it means

Raised by MistralAIChatCompletion.__init__ after settings validate but chat_model_id resolves to a falsy value. Without a model id the service cannot target a Mistral model, so initialization aborts even though credentials are valid.

Source

Thrown at python/semantic_kernel/connectors/ai/mistral_ai/services/mistral_ai_chat_completion.py:97

            api_key : The optional API key to use. If provided will override,
                the env vars or .env file value.
            async_client : An existing client to use.
            env_file_path : Use the environment settings file as a fallback
                to environment variables.
            env_file_encoding : The encoding of the environment settings file.
        """
        try:
            mistralai_settings = MistralAISettings(
                api_key=api_key,
                chat_model_id=ai_model_id,
                env_file_path=env_file_path,
                env_file_encoding=env_file_encoding,
            )
        except ValidationError as ex:
            raise ServiceInitializationError("Failed to create MistralAI settings.", ex) from ex

        if not mistralai_settings.chat_model_id:
            raise ServiceInitializationError("The MistralAI chat model ID is required.")

        if not async_client:
            async_client = Mistral(
                api_key=mistralai_settings.api_key.get_secret_value(),
            )

        super().__init__(
            async_client=async_client,
            service_id=service_id or mistralai_settings.chat_model_id,
            ai_model_id=ai_model_id or mistralai_settings.chat_model_id,
        )

    # region Overriding base class methods

    # Override from AIServiceClientBase
    @override
    def get_prompt_execution_settings_class(self) -> "type[MistralAIChatPromptExecutionSettings]":
        """Create a request settings object."""

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Pass ai_model_id explicitly to MistralAIChatCompletion (e.g. 'mistral-large-latest').
2. Set the chat model id via environment variable / .env.
3. Confirm the model id is non-empty and references a valid Mistral model.

Example fix

# before
svc = MistralAIChatCompletion(api_key=os.environ['MISTRAL_API_KEY'])
# after
svc = MistralAIChatCompletion(api_key=os.environ['MISTRAL_API_KEY'], ai_model_id='mistral-large-latest')

model_id = os.environ.get('MISTRAL_CHAT_MODEL_ID') or passed_model_id
assert model_id, 'MistralAI chat model ID is required'

When it happens

Trigger: Constructing MistralAIChatCompletion without ai_model_id and no chat model env var. Passing an empty string for the model id.

Common situations: Forgetting to set the model id env var. Assuming a default model. Sample code that omits the model argument while .env doesn't define it.

Related errors

• The Google AI Gemini model ID is required.
• The Vertex AI Gemini model ID is required.
• The Vertex AI Gemini model ID is required.
• The Vertex AI embedding model ID is required.
• Failed to create MistralAI settings.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/198de84fcd1f6baf. Report an issue: GitHub.