microsoft/semantic-kernel · error · NotImplementedError

Unable to create channel. Channel type not configured.

Error message

Unable to create channel. Channel type not configured.

What it means

Agent.create_channel() instantiates self.channel_type() to give the agent a communication channel; if the subclass never set channel_type (None on the base), it raises NotImplementedError. This is the async sibling of error 695 and fires when the chat runtime asks the agent to produce its channel.

Source

Thrown at python/semantic_kernel/agents/agent.py:436

    def get_channel_keys(self) -> Iterable[str]:
        """Get the channel keys.

        Returns:
            A list of channel keys.
        """
        if not self.channel_type:
            raise NotImplementedError("Unable to get channel keys. Channel type not configured.")
        yield self.channel_type.__name__

    async def create_channel(self) -> AgentChannel:
        """Create a channel.

        Returns:
            An instance of AgentChannel.
        """
        if not self.channel_type:
            raise NotImplementedError("Unable to create channel. Channel type not configured.")
        return self.channel_type()

    # endregion

    # region Instructions Management

    async def format_instructions(self, kernel: Kernel, arguments: KernelArguments | None = None) -> str | None:
        """Format the instructions.

        Args:
            kernel: The kernel instance.
            arguments: The kernel arguments.

        Returns:
            The formatted instructions.
        """
        if self.prompt_template is None:
            if self.instructions is None:

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Set channel_type on your custom Agent subclass to a concrete AgentChannel type.
2. Use a built-in concrete agent which already configures its channel.
3. Avoid instantiating the abstract Agent base.

Example fix

# before
class MyAgent(Agent):
    ...  # no channel_type -> create_channel() errors
# after
from semantic_kernel.agents.channels.chat_history_channel import ChatHistoryChannel
class MyAgent(Agent):
    channel_type: ClassVar[type[AgentChannel]] = ChatHistoryChannel

assert agent.channel_type is not None, \
    f'{type(agent).__name__} has no channel_type; cannot create_channel()'

from semantic_kernel.agents.channels.agent_channel import AgentChannel
def agent_has_channel(agent) -> bool:
    ct = getattr(type(agent), 'channel_type', None)
    return ct is not None and issubclass(ct, AgentChannel)

When it happens

Trigger: Adding a custom/base agent to a group chat that calls create_channel(); instantiating Agent directly; a subclass missing the channel_type ClassVar.

Common situations: Building a custom agent without specifying channel_type; using the abstract base; copy-pasting a subclass and dropping the channel declaration.

Related errors

• Unable to get channel keys. Channel type not configured.
• The message could not be added to the thread due to an error
• Agent with name {agentId.Type} not found.
• module {__name__} has no attribute {name}
• Thread has been deleted; call `create()` to recreate it.

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/73f0652fa9106633. Report an issue: GitHub.