ERR_PACKAGE_PATH_NOT_EXPORTED with @modelcontextprotocol/express

[maximemoreillon]

Describe the bug

I am getting a ERR_PACKAGE_PATH_NOT_EXPORTED with message No "exports" main defined in C:\Users\myusersmyproject\node_modules\@modelcontextprotocol\express\package.json when running the @modelcontextprotocol/express example as per the usage guide here

import { createMcpExpressApp } from '@modelcontextprotocol/express';
const app = createMcpExpressApp();

This looks similar to #726 , #427

To Reproduce

Node version 24.14.1 LTS on Windows 11.

Project initialized with

npm i -D typescript
npx tsc --init

verbatimModuleSyntax commented out in tsconfig

Expected behavior

Having no error

Additional context

Dependencies:

{
  // ...
  "dependencies": {
    "@modelcontextprotocol/express": "^2.0.0-alpha.2",
    "@modelcontextprotocol/node": "^2.0.0-alpha.2",
    "@modelcontextprotocol/server": "^2.0.0-alpha.2",
    "express": "^5.2.1"
  },
  "devDependencies": {
    "@types/express": "^5.0.6",
    "typescript": "^6.0.2"
  }
}