ModuleNotFoundError: No module named 'uvicorn'

[nicosuave]

I'm needing to manually add uvicorn to my package to run in dev mode.

Then when installed in Claude desktop I just see the following in Claude logs

ModuleNotFoundError: No module named 'uvicorn' in claude logs stemming from site-packages/fastmcp/server.py

[marcusmotill]

I am not a uv god so def a little confused on how this bundling works but I was able to overcome this error my using the --with flag:
uv run fastmcp install --with uvicorn server.py

[paquino11]

Got the same issue while following the quickstart, by running the following command worked for me
uv run fastmcp install --with uvicorn server.py
uv run fastmcp dev --with uvicorn server.py

[boukeversteegh]

This problem doesn't only affect uvicorn, but possibly all projects dependencies, because -- if i understand correctly -- the way the fastmcp install works now, is that it doesn't run from the project directory, so all your pyproject.toml dependencies are ignored.

I was able to fix this by editing the generated mcp settings file as follows:

    "My MCP Server": {
      "command": "uv",
      "args": [
        "run",
-       "--with"
-       "uvicorn"
-       "--with"
-       "another-dependency"
+       "--project",
+       "C:\\my-mcp-server-project",
        "fastmcp",
        "run",
        "C:\\my-mcp-server-project\\server.py"
      ]
    }

To avoid the uvicorn depedency problem, you need to run uv add uvicorn within your project once. This will install it in the toml file, and it will be picked up the above command.