| @modelcontextprotocol/core-internal | patch |
|---|---|
| @modelcontextprotocol/server | patch |
Pin the modern (2026-07-28) HTTP serving path's rejection codes to the assignments the published conformance suite asserts: a header/body cross-check mismatch (MCP-Protocol-Version or Mcp-Method disagreeing with the request body) is now rejected with -32020 (HeaderMismatch), and a request whose protocol-version header names a modern revision but whose body is missing the _meta envelope (or its required protocol-version key) is rejected with -32602 invalid params naming the missing key(s). Both keep HTTP 400. These cells previously emitted a provisional -32004 while the upstream error-code discussion was open. The envelope-less rejection on a modern-only endpoint (-32022 with the supported-versions list), the 2025-era serving paths, and the client-side probe handling are unchanged.