microsoft/semantic-kernel · error · RuntimeError

Function call required but no function steps found for agent

Error message

Function call required but no function steps found for agent `{agent.name}` thread: {thread_id}.

What it means

Raised as a RuntimeError during streaming when a ThreadRun transitions to 'requires_action' with a SubmitToolOutputsAction, but _handle_streaming_requires_action returns None (no function call contents could be extracted from the run's required_action). The framework needs function steps to emit tool-call streaming content, so their absence is an internal inconsistency it cannot proceed past.

Source

Thrown at python/semantic_kernel/agents/azure_ai/agent_thread_actions.py:703

                elif event_type == AgentStreamEvent.THREAD_RUN_REQUIRES_ACTION:
                    logger.debug(
                        f"Entering step type {event_type}, agent `{agent.name}` and "
                        f"thread `{thread_id}` with event data: {event_data}"
                    )
                    run = cast(ThreadRun, event_data)

                    # Check if this is a function call request
                    if isinstance(run.required_action, SubmitToolOutputsAction):
                        action_result = await cls._handle_streaming_requires_action(
                            agent_name=agent.name,
                            kernel=kernel,
                            run=run,
                            function_steps=function_steps,
                            arguments=arguments,
                            function_choice_behavior=function_choice_behavior,
                        )
                        if action_result is None:
                            raise RuntimeError(
                                f"Function call required but no function steps found for agent `{agent.name}` "
                                f"thread: {thread_id}."
                            )

                        for content in (
                            action_result.function_call_streaming_content,
                            action_result.function_result_streaming_content,
                        ):
                            if content and output_messages is not None:
                                if thread_msg_id and THREAD_MESSAGE_ID not in content.metadata:
                                    content.metadata[THREAD_MESSAGE_ID] = thread_msg_id
                                output_messages.append(content)

                        handler: BaseAsyncAgentEventHandler = AsyncAgentEventHandler()
                        await agent.client.agents.runs.submit_tool_outputs_stream(
                            run_id=run.id,
                            thread_id=thread_id,
                            tool_outputs=action_result.tool_outputs,  # type: ignore

View on GitHub (pinned to c028a0c7dc)

Solutions

Upgrade semantic-kernel and the azure-ai SDK to aligned versions so requires_action payloads are parsed correctly.
Disable auto function calling for the call if you do not need it, avoiding the requires_action path.
Inspect run.required_action at debug level to confirm the tool-call payload shape and report if it diverges from the wrapper's expectations.

Defensive patterns

Strategy: try-catch

Try / catch

try:
    async for chunk in agent.invoke_stream(thread=thread):
        ...
except RuntimeError as e:
    if 'no function steps found' in str(e):
        logger.error('requires_action yielded no function steps; check azure-ai SDK compatibility')
        # fall back to non-streaming invoke without auto function calling
    raise

Prevention

Align semantic-kernel and azure-ai SDK versions so requires_action payloads parse.
Disable auto function calling if you do not rely on it, to avoid the requires_action path.

When it happens

Trigger: Azure returns a requires_action run whose tool call payload is empty or shaped in a way get_function_call_contents cannot parse, so function_steps yields nothing and action_result is None.

Common situations: Azure SDK version producing a required_action structure the wrapper does not expect; a run that requires action but carries no tool calls (edge server behavior); partial/ malformed run object during streaming.

Related errors

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/582ed19879237ed7. Report an issue: GitHub.