microsoft/autogen · error · RuntimeError

MessageHandlerContext cannot be instantiated. It is a static

Error message

MessageHandlerContext cannot be instantiated. It is a static class that provides context management for message handling.

What it means

Error "MessageHandlerContext cannot be instantiated. It is a static class that provides context management for message handling." thrown in microsoft/autogen.

Source

Thrown at python/packages/autogen-core/src/autogen_core/_message_handler_context.py:10

from contextlib import contextmanager
from contextvars import ContextVar
from typing import Any, ClassVar, Generator

from ._agent_id import AgentId


class MessageHandlerContext:
    def __init__(self) -> None:
        raise RuntimeError(
            "MessageHandlerContext cannot be instantiated. It is a static class that provides context management for message handling."
        )

    _MESSAGE_HANDLER_CONTEXT: ClassVar[ContextVar[AgentId]] = ContextVar("_MESSAGE_HANDLER_CONTEXT")

    @classmethod
    @contextmanager
    def populate_context(cls, ctx: AgentId) -> Generator[None, Any, None]:
        """:meta private:"""
        token = MessageHandlerContext._MESSAGE_HANDLER_CONTEXT.set(ctx)
        try:
            yield
        finally:
            MessageHandlerContext._MESSAGE_HANDLER_CONTEXT.reset(token)

    @classmethod
    def agent_id(cls) -> AgentId:
        try:

View on GitHub (pinned to 027ecf0a37)

Solutions

1. Do not instantiate; use its static accessors within a handler

Example fix

Call MessageHandlerContext.agent_id() only inside a message handler

When it happens

Trigger: Thrown at python/packages/autogen-core/src/autogen_core/_message_handler_context.py:10 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/autogen@027ecf0a37 (2026-08-15). Data as JSON: /api/errors/be00db0af4019f7e. Report an issue: GitHub.