{"version":"2.1.221","anchor":"custom-mcp-notification-handlers-skipped-on-modern-era-conne","canonical_anchor":"custom-mcp-notification-handlers-skipped-on-modern-era-conne","heading":"Custom MCP notification handlers skipped on modern-era connections","tier":"soon","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/custom-mcp-notification-handlers-skipped-on-modern-era-conne","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Custom MCP notification handlers skipped on modern-era connections\n\nMCP servers using a newer protocol era no longer get custom notification handlers, and you see a warning.\n\n**What**\n\nRegistering a handler for an unsolicited custom notification is refused when the connection negotiated a modern protocol era, because there is no delivery path for it.\n\n**Details**\n\n- Emits a warning naming the server, the method and the negotiated revision.\n- In 2.1.220 the handler was always registered; `getProtocolEra` does not appear in that build.\n- Only reachable when era negotiation is on, see the tengu_mcp_protocol_negotiation_* flags.\n\n**Evidence**\n\n`which has no delivery path for unsolicited custom notifications`\n\n- Area: MCP\n- Tier: Nothing to try yet\n- Useful: 2\/5\n- Signal: 2\/5\n- Present in the build but not switched on"}