microsoft/semantic-kernel · error · ValueError

Unknown destination type: {type(destination)}

Error message

Unknown destination type: {type(destination)}

What it means

Raised by the tracer's _get_destination_str when the destination is not one of the four supported types: AgentId, TopicId, str, or None. The method maps a messaging destination to a string for the span name; any other type raises ValueError.

Source

Thrown at python/semantic_kernel/agents/runtime/core/telemetry/tracing_config.py:190

            SpanKind: The span kind based on the messaging operation.
        """
        if operation in ["create", "send", "publish"]:
            return SpanKind.PRODUCER
        if operation in ["receive", "intercept", "process", "ack"]:
            return SpanKind.CONSUMER
        return SpanKind.CLIENT

    # TODO(evmattso): Use stringified convention
    def _get_destination_str(self, destination: MessagingDestination) -> str:
        if isinstance(destination, AgentId):
            return f"{destination.type}.({destination.key})-A"
        if isinstance(destination, TopicId):
            return f"{destination.type}.({destination.source})-T"
        if isinstance(destination, str):
            return destination
        if destination is None:
            return ""
        raise ValueError(f"Unknown destination type: {type(destination)}")

    def _get_operation_type(self, operation: MessagingOperation) -> str:
        if operation in ["send", "publish"]:
            return "publish"
        if operation in ["create"]:
            return "create"
        if operation in ["receive", "intercept", "ack"]:
            return "receive"
        if operation in ["process"]:
            return "process"
        return "Unknown"

View on GitHub (pinned to c028a0c7dc)

Solutions

1. Pass an AgentId, TopicId, str, or None as the destination.
2. Convert custom destinations to a string before tracing.
3. Extend the tracer configuration if a new destination type is genuinely needed.

Example fix

// before
span = tracer.start_span(destination={'type': 'x', 'key': 'y'})  # dict -> ValueError

// after
span = tracer.start_span(destination=AgentId(type='x', key='y'))

def is_supported_destination(d) -> bool:
    from semantic_kernel.agents.runtime.core import AgentId, TopicId
    return d is None or isinstance(d, (AgentId, TopicId, str))

from semantic_kernel.agents.runtime.core import AgentId, TopicId

def is_messaging_destination(d) -> bool:
    return d is None or isinstance(d, (AgentId, TopicId, str))

When it happens

Trigger: Passing a destination object that is not AgentId, TopicId, str, or None: a custom destination class, a dict, an int, or a tuple.

Common situations: Custom runtime integrations that introduce new destination types without extending the tracer; passing a raw dict or primitive as a destination.

Related errors

• Configuration key '{section}:{key}' not found
• Sample plugin path not found.
• AI service not recognized.
• Unknown metadata type: {type(metadata)}

AI-assisted analysis of microsoft/semantic-kernel@c028a0c7dc (2026-08-13). Data as JSON: /api/errors/fb140e8bc8902656. Report an issue: GitHub.