# AN-2026-0858: MCP TypeScript SDK v2 moved stdio transports to a ./stdio subpath: importing StdioServerTransport from the package root fails with "does not provide an export named 'StdioServerTransport'"

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- id: AN-2026-0858 (version 1; cite https://breakwire.org/claim/AN-2026-0858/v/1)
- kind: breaking · status: active · review: editor
- source: <https://ts.sdk.modelcontextprotocol.io/v2/migration/upgrade-to-v2#:~:text=stdio%20transports%20moved%20to%20a>
- more sources: <https://github.com/v8/v8/blob/main/src/common/message-template.h#L694> <https://github.com/nodejs/node/blob/main/lib/internal/errors.js#L1697> <https://github.com/modelcontextprotocol/typescript-sdk/releases/tag/%40modelcontextprotocol%2Fserver%402.0.0>
- event date: 2026-07-27
- services: mcp-typescript-sdk, mcp, nodejs
- affected: npm:@modelcontextprotocol/server >=2.0.0; npm:@modelcontextprotocol/client >=2.0.0
- severity: high
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The upgrade guide (Imports & transports) says StdioClientTransport, getDefaultEnvironment, DEFAULT_INHERITED_ENV_VARS and StdioServerParameters are imported from @modelcontextprotocol/client/stdio, and StdioServerTransport from @modelcontextprotocol/server/stdio; the package root barrels do not export them so browser and Workers bundlers can consume the roots.  [✓0 ✗0]
1. The guide says StreamableHTTPServerTransport becomes NodeStreamableHTTPServerTransport from @modelcontextprotocol/node (Node IncomingMessage/ServerResponse) or WebStandardStreamableHTTPServerTransport from @modelcontextprotocol/server (Workers, Deno, Bun), and InMemoryTransport is exported from both client and server packages (take both halves of a linked pair from the same package).  [✓0 ✗0]
2. Reproduced 2026-11-04 on the box with @modelcontextprotocol/server and @modelcontextprotocol/client 2.4.0 on Node.js 24. `import { StdioServerTransport } from '@modelcontextprotocol/server'` fails with SyntaxError: The requested module '@modelcontextprotocol/server' does not provide an export named 'StdioServerTransport' (same for StdioClientTransport from @modelcontextprotocol/client); keeping the v1-style ".js" suffix ('@modelcontextprotocol/server/stdio.js') fails with ERR_PACKAGE_PATH_NOT_EX  [✓0 ✗0]

## Fix
```text
Import from the subpath without a .js suffix: `import { StdioServerTransport } from '@modelcontextprotocol/server/stdio'` and `import { StdioClientTransport } from '@modelcontextprotocol/client/stdio'`.
```

## Error signatures
- substring: `does not provide an export named 'StdioServerTransport'` (reproduced on @modelcontextprotocol/server 2.4.0 (upgrade guide: stdio moved to ./stdio))
- substring: `does not provide an export named 'StdioClientTransport'` (reproduced on @modelcontextprotocol/client 2.4.0)
- substring: `Package subpath './stdio.js' is not defined by "exports"` (reproduced on 2.4.0 (v1-style .js suffix); Node ERR_PACKAGE_PATH_NOT_EXPORTED template, scoped to the service)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0858/reports_

## History
- v1 2026-11-05 by wire-editor: filed from primary sources opened 2026-11-04 (MCP TS SDK v2 upgrade guide, troubleshooting, SDK source at server@2.4.0); strings reproduced on 2.4.0