## Cause
subscriptions/listen is era-gated in the SDK; default negotiation lands on 2025-11-25 unless versionNegotiation is configured for modern era.
## Steps
1. Confirm SdkError code METHOD_NOT_SUPPORTED_BY_PROTOCOL_VERSION and message naming subscriptions/listen and negotiated 2025-11-25.
2. If subscriptions/listen is required: recreate Client with versionNegotiation: { mode: 'auto' } and connect to a 2026-07-28-capable server; verify negotiated era before calling listen().
3. If staying on 2025 era: remove listen(); enable ClientOptions.listChanged and use resources/subscribe for change notifications.
4. Do not treat this as a server bug—no request reaches the transport.
## Expected result
Either listen() succeeds on a 2026-07-28-era session or 2025-era change notifications work via listChanged/resources/subscribe without local SDK rejection.
## Misleading approaches
- Investigating server-side subscription bugs when the error is raised locally pre-transport.
- Calling listen() without negotiating 2026-07-28 on either client or server.
## Limitations
- Server must actually support 2026-07-28 for the auto-negotiation path to enable listen().
- Other METHOD_NOT_SUPPORTED_BY_PROTOCOL_VERSION messages may reference different methods.
## Unknowns
- Target server's highest supported protocol revision without live server/discover.
## Evidence claims
- (documented_platform_behavior) subscriptions/listen requires a 2026-07-28-era connection; default client negotiation yields 2025-11-25. — https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/docs/troubleshooting.md
- (documented_platform_behavior) The SDK raises METHOD_NOT_SUPPORTED_BY_PROTOCOL_VERSION locally before the transport sends the method. — https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/docs/troubleshooting.md
- (documented_workaround) Documented fixes are versionNegotiation auto against a 2026-07-28 server or listChanged/resources/subscribe on 2025 era. — https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/docs/troubleshooting.md
Proposed approach
- Problem id
- df47514d-32f1-4478-8138-7550c3b6fd5f
- Proposed action
- Either connect with versionNegotiation: { mode: 'auto' } against a server that serves 2026-07-28, or on 2025-era connections use ClientOptions.listChanged with resources/subscribe instead of listen().
- Applicability
- State
- partial
- Text
- @modelcontextprotocol/client v2 after default connect() (2025-11-25 era) when calling client.listen({ resourceSubscriptions: [...] }).; affected: MCP TypeScript SDK v2 client; fix_status: CONFIRMED_SOLUTION
- Limitations
- State
- partial
- Text
- Server must actually support 2026-07-28 for the auto-negotiation path to enable listen(). Other METHOD_NOT_SUPPORTED_BY_PROTOCOL_VERSION messages may reference different methods.
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- @modelcontextprotocol/client v2 after default connect() (2025-11-25 era) when calling client.lis
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