fastmcp.run() runtimeerror: task group is not initialized. make sure to use run().

[SinDongHwan]

Initial Checks

• I confirm that I'm using the latest version of MCP Python SDK
• I confirm that I searched for my issue in https://github.com/modelcontextprotocol/python-sdk/issues before opening this issue

Description

following error sometime occur.

fastmcp.run() runtimeerror: task group is not initialized. make sure to use run().

Example Code

from mcp.server.fastmcp import FastMCP
# FastMCP instance
mcp = FastMCP(
    name=setting.server["name"],
    host=setting.server["host"],
    port=setting.server["port"],
    streamable_http_path=setting.server["streamable_http_path"],
    api_route="/mcp/",
    debug=True,
)
try:
    mcp.run(transport="streamable-http")
except KeyboardInterrupt:
    logger.info("Service shut down")

Python & MCP Python SDK

mcp version (1.13.1)

[ChenyangLi4288]

I can't reproduce this one.

[felixweinberger]

I can't reproduce this one.

I was also unable to reproduce this - could you provide any more information about your setup? Are you running into this issue with just the example code given and running python -m main.py?

[tugbayatilla]

i just copy and paste this code block, and got the same result.

https://github.com/modelcontextprotocol/python-sdk/blob/main/examples/snippets/servers/streamable_http_multiple_servers.py

i have just installed these 2 packages
mcp[cli]
ally-ai-core

python: 3.12

`Package Version

---

ally-ai-core 0.7.0
annotated-types 0.7.0
anyio 4.11.0
attrs 25.4.0
certifi 2025.10.5
click 8.3.0
h11 0.16.0
httpcore 1.0.9
httpx 0.28.1
httpx-sse 0.4.3
idna 3.11
jsonschema 4.25.1
jsonschema-specifications 2025.9.1
markdown-it-py 4.0.0
mcp 1.19.0
mdurl 0.1.2
pip 25.3
pydantic 2.12.3
pydantic_core 2.41.4
pydantic-settings 2.11.0
Pygments 2.19.2
python-dotenv 1.2.1
python-multipart 0.0.20
PyYAML 6.0.3
referencing 0.37.0
rich 14.2.0
rpds-py 0.28.0
shellingham 1.5.4
sniffio 1.3.1
sse-starlette 3.0.2
starlette 0.49.1
typer 0.20.0
typing_extensions 4.15.0
typing-inspection 0.4.2
uvicorn 0.38.0
`

[maxisbey]

Thanks for the report. I'm closing this out as part of a backlog cleanup now that v2 is out. Feel free to reopen if this is still relevant.