Issue evidence · AI API · langgenius/dify

MCP client rejects protocol version 2025-11-25 during initialize

Confirmed from source (not run)

Dify's MCP client raises on an initialize result with protocolVersion 2025-11-25 and does not create the server.

What Badgr ran

Read api/core/mcp/entities.py and api/core/mcp/session/client_session.py on Dify's main branch. Not run: no MCP server or Dify instance was used.

SUPPORTED_PROTOCOL_VERSIONS is ["2024-11-05", "2025-03-26", LATEST_PROTOCOL_VERSION] and LATEST_PROTOCOL_VERSION is "2025-06-18".
client_session.py line 143 raises RuntimeError("Unsupported protocol version from the server: ...") for any other version.

Code reading only (not run): the handshake failure itself was not replayed.

Checked 2026-10-14 in Badgr’s local development environment.