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Updated error handling to throw ProtocolError for invalid parameters instead of a generic Error.
With spec-method schema failures now answered as -32602 Invalid params, the logging:set-level:invalid-level e2e scenarios pass; the knownFailures block encoded the old -32603 surface.
Pins the fix for modelcontextprotocol#2284: logging/setLevel with a schema-invalid level answers -32602 Invalid params (not -32603 Internal error) through packages/server.
Update spec-method error responses to return -32602 for invalid parameters instead of -32603. This aligns with JSON-RPC 2.0 specifications.
🦋 Changeset detectedLatest commit: a1899fd The changes in this PR will be included in the next version bump. This PR includes changesets to release 6 packages
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@modelcontextprotocol/client
@modelcontextprotocol/codemod
@modelcontextprotocol/core
@modelcontextprotocol/server
@modelcontextprotocol/server-legacy
@modelcontextprotocol/express
@modelcontextprotocol/fastify
@modelcontextprotocol/hono
@modelcontextprotocol/node
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Rebased locally onto current origin/main (at 8aabbdc) and verified all 6 commits apply with zero merge conflicts.
This cleanly resolves #2916 and #2284:
- Spec-method requests with invalid params now return ProtocolErrorCode.InvalidParams (-32602) instead of ProtocolErrorCode.InternalError (-32603), aligning the two-argument setRequestHandler path with the three-argument path and tools/call.
- The regression test in packages/server/test/server/specMethodInvalidParams.test.ts verifies logging/setLevel rejection with error.code === -32602 and the expected error message.
- The dispatch-rejection fixture invalid-spec-params.json correctly pins -32602.
- The stale knownFailures entry for logging:set-level:invalid-level in test/e2e/requirements.ts is cleanly removed.
- All 14 CI matrix checks passed.
Ready for maintainer merge.
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Closes #2284.
Motivation and Context
When a spec-defined method (e.g.
logging/setLevel) received params that fail the method's wire schema, the server answered-32603Internal error. Per JSON-RPC 2.0, invalid method parameters are the caller's error and should be-32602Invalid params. The old surface told callers the server broke when in fact their request was malformed.Before the function-only
WireCodeccontract, the Zod parse threw out of the handler and the funnel mapped it to-32603. Custom handlers registered with a params schema already answered-32602; this change makes spec methods match that surface.Root cause is a single throw in the spec-method dispatch closure in
protocol.ts— it re-threw the schema failure as a bareError(funnelled to-32603) instead of aProtocolError(InvalidParams).How Has This Been Tested?
packages/server/test/server/specMethodInvalidParams.test.ts: aServerwith the logging capability + alogging/setLevelhandler; after the initialize handshake, sendinglogging/setLevel { level: 'not-a-level' }now yieldserror.code === -32602and a message containingInvalid params for logging/setLevel.invalid-spec-params.jsonis updated to pin-32602.knownFailuresblock forlogging:set-level:invalid-levelencoding the old-32603behavior; with the fix those e2e scenarios pass, so the staleknownFailuresentry is removed (otherwise the "expected to fail" scenarios error out).pnpm lint:allandpnpm test:allpass locally.Breaking Changes
Wire-visible: peers that matched on
-32603for schema-invalid spec-method params will now observe-32602. This is intentional and brings spec methods in line with the custom-handler path. A changeset (patchto core-internal, client, core, server) is included.Types of changes
Checklist
pnpm changeset)