Cannot find package '@modelcontextprotocol/sdk'

What it means

The TypeScript SDK v2 split @modelcontextprotocol/sdk into @modelcontextprotocol/server, @modelcontextprotocol/client and adapter packages. Code from a v1 tutorial fails at import time. We installed only @modelcontextprotocol/server 2.4.0 and ran three typical v1 imports:

v1 import	Error
from '@modelcontextprotocol/sdk/server/mcp.js'	Error [ERR_MODULE_NOT_FOUND]: Cannot find package '@modelcontextprotocol/sdk' imported from …
from '@modelcontextprotocol/server/mcp.js'	Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './mcp.js' is not defined by "exports" in …/@modelcontextprotocol/server/package.json
import { StdioServerTransport } from '@modelcontextprotocol/server'	SyntaxError: The requested module '@modelcontextprotocol/server' does not provide an export named 'StdioServerTransport'

The process exits before it can answer, so a client shows Connection closed.

v1 import paths with v2 installed

v2 has no deep paths such as /server/mcp.js or /server/stdio.js. Import from the package root, or from the few subpaths it exports:

// v1
import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';

// v2
import { McpServer } from '@modelcontextprotocol/server';
import { serveStdio } from '@modelcontextprotocol/server/stdio';

If you are not ready to migrate, install v1 on purpose: npm install @modelcontextprotocol/sdk@1. It is still published (1.32.2 at the time of writing) and its clients talk to v2 servers.

v1 names that v2 removed

Some v1 classes are gone, so the name is missing even from the right package. StdioServerTransport with server.connect() became serveStdio(factory); the Node.js HTTP transport moved to @modelcontextprotocol/node. Follow Upgrade from TypeScript SDK v1 to v2 rather than renaming imports one by one.

Related

• Your first server in TypeScript: a complete v2 server.