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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ClosedResourceError During MCP Stateless Server Shutdown When Sending Log Messages","articleBody":"### Initial Checks\n\n- [x] I confirm that I'm using the latest version of MCP Python SDK\n- [x] I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue\n\n### Description\n\nI'm seeing occasional errors from our MCP server, which I think are a race condition during shutdown. \n\nI think this is a similar but distinct issue to the race condition in #1190 and #1384 as this is during `send_log_message`\n\nI haven't been able to get a consistent reproduce yet, will update when I can.\n\n## Stack Trace\n\n```python\n+ Exception Group Traceback (most recent call last):\n  |   File \"/app/.venv/lib/python3.13/site-packages/mcp/server/streamable_http_manager.py\", line 180, in run_stateless_server\n  |     await self.app.run(\n  |     ...\u003c4 lines\u003e...\n  |     )\n  |   File \"/app/.venv/lib/python3.13/site-packages/fastmcp/server/low_level.py\", line 202, in run\n  |     async with AsyncExitStack() as stack:\n  |                ~~~~~~~~~~~~~~^^\n  |   File \"/usr/local/lib/python3.13/contextlib.py\", line 768, in __aexit__\n  |     raise exc\n  |   File \"/usr/local/lib/python3.13/contextlib.py\", line 751, in __aexit__\n  |     cb_suppress = await cb(*exc_details)\n  |                   ^^^^^^^^^^^^^^^^^^^^^^\n  |   File \"/app/.venv/lib/python3.13/site-packages/mcp/shared/session.py\", line 238, in __aexit__\n  |     return await self._task_group.__aexit__(exc_type, exc_val, exc_tb)\n  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  |   File \"/app/.venv/lib/python3.13/site-packages/anyio/_backends/_asyncio.py\", line 783, in __aexit__\n  |     raise BaseExceptionGroup(\n  |         \"unhandled errors in a TaskGroup\", self._exceptions\n  |     ) from None\n  | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)\n  +-+---------------- 1 ----------------\n    | Exception Group Traceback (most recent call last):\n    |   File \"/app/.venv/lib/python3.13/site-packages/fastmcp/server/low_level.py\", line 214, in run\n    |     async with anyio.create_task_group() as tg:\n    |                ~~~~~~~~~~~~~~~~~~~~~~~^^\n    |   File \"/app/.venv/lib/python3.13/site-packages/anyio/_backends/_asyncio.py\", line 783, in __aexit__\n    |     raise BaseExceptionGroup(\n    |         \"unhandled errors in a TaskGroup\", self._exceptions\n    |     ) from None\n    | ExceptionGroup: unhandled errors in a TaskGroup (1 sub-exception)\n    +-+---------------- 1 ----------------\n      | Traceback (most recent call last):\n      |   File \"/app/.venv/lib/python3.13/site-packages/mcp/server/lowlevel/server.py\", line 694, in _handle_message\n      |     await session.send_log_message(\n      |     ...\u003c3 lines\u003e...\n      |     )\n      |   File \"/app/.venv/lib/python3.13/site-packages/mcp/server/session.py\", line 213, in send_log_message\n      |     await self.send_notification(\n      |     ...\u003c10 lines\u003e...\n      |     )\n      |   File \"/app/.venv/lib/python3.13/site-packages/mcp/shared/session.py\", line 335, in send_notification\n      |     await self._write_stream.send(session_message)\n      |   File \"/app/.venv/lib/python3.13/site-packages/anyio/streams/memory.py\", line 249, in send\n      |     self.send_nowait(item)\n      |     ~~~~~~~~~~~~~~~~^^^^^^\n      |   File \"/app/.venv/lib/python3.13/site-packages/anyio/streams/memory.py\", line 218, in send_nowait\n      |     raise ClosedResourceError\n      | anyio.ClosedResourceError\n      +------------------------------------\n```\n\n### Python \u0026 MCP Python SDK\n\n**MCP SDK Version**: 1.25.0\nvia **fastmcp Version**: 2.14.4\n**Python Version**: 3.13.5\n","author":{"url":"https://github.com/jonfinerty","@type":"Person","name":"jonfinerty"},"datePublished":"2026-01-27T20:55:08.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/1967/python-sdk/issues/1967"}