ModuleNotFoundError: No module named 'httpx'

[MalcomRdg]

Describe the bug
Following all the instruction from https://modelcontextprotocol.io/quickstart/server#what-we%E2%80%99ll-be-building and https://modelcontextprotocol.io/quickstart/client. When running the client , It always show

import httpx
ModuleNotFoundError: No module named 'httpx'

I checked many times and I have everything installed properly even httpx and this is well accessible from my uv.

To Reproduce.
Steps to reproduce the behavior:

1. create server on its own directory with its own uv venv
2. create the client by following https://modelcontextprotocol.io/quickstart/client on another folder of the same parent directory , creating again its own uv venv

Expected behavior
not import error , just running the code properly

Logs
If applicable, add logs to help explain your problem.

Additional context
Add any other context about the problem here.

[TfiyuenLau]

Have you solved it now? I have the same problem.
It seems that this method does not make the McpServer run in the correct UV virtual environment.

[TfiyuenLau]

OK. I fixed this bug by modifying the client sample code to uv run to execute the Python mcpserver script.

before:

    command = "python" if is_python else "node"
    server_params = StdioServerParameters(
        command=command,
        args=[server_script_path],
        env=None
    )

after:

    command = "uv" if is_python else "node"
    server_params = StdioServerParameters(
        command=command,
        args=["run", server_script_path],
        env=None
    )

[real-jiakai]

I successfully resolved the "ModuleNotFoundError: No module named 'httpx'" issue by modifying line 31 in the client.py code referenced at https://github.com/modelcontextprotocol/quickstart-resources/blob/main/mcp-client-python/client.py#L31.

Original code:

command = "python" if is_python else "node"

My solution:

command = "C:\\Users\\Administrator\\weather\\.venv\\Scripts\\python" if is_python else "node"

The issue occurs because Python virtual environments are isolated containers with their own package installations. When using the generic python command, the system uses whatever Python interpreter is first in your PATH, which doesn't have access to packages installed in your MCP server's virtual environment.

By explicitly specifying the full path to the Python interpreter inside the server's virtual environment, we ensure the server script runs with access to all packages installed in that environment, including httpx.

[ChiNoel-osu]

I successfully resolved the "ModuleNotFoundError: No module named 'httpx'" issue by modifying line 31 in the client.py code referenced at https://github.com/modelcontextprotocol/quickstart-resources/blob/main/mcp-client-python/client.py#L31.

Original code:

command = "python" if is_python else "node"

My solution:

command = "C:\Users\Administrator\weather\.venv\Scripts\python" if is_python else "node"

The issue occurs because Python virtual environments are isolated containers with their own package installations. When using the generic python command, the system uses whatever Python interpreter is first in your PATH, which doesn't have access to packages installed in your MCP server's virtual environment.

By explicitly specifying the full path to the Python interpreter inside the server's virtual environment, we ensure the server script runs with access to all packages installed in that environment, including httpx.

command = sys.executable if is_python else "node" may also work if script is ran from a venv.

[alfa-f]

Another option if :

• you want to avoid editing the source
• you want to avoid hardcoding interpreter paths
• you have conda installed on your machine

Create an env, 'mcp-weather' using conda, install both sets of deps to that env, then activate it and run the client command.

conda create -n mcp-weather
conda activate mcp-weather
cd <your-dir>\quickstart-resources\mcp-client-python
pip install .
cd <your-dir>\quickstart-resources\weather-server-python
pip install .
cd <your-dir>\quickstart-resources\mcp-client-python
python client.py ../weather-server-python/weather.py