n8n MCP Client node ends sessions: what that means for Sume
n8n 2.42.0 terminates the MCP session before closing the client. Sume's endpoint is POST-only and issues no session id, so pair it with idempotency keys.
n8n 2.42.0, published 2026-09-29, lists a fix for the MCP Client node: "Terminate session before closing the client". For Sume this changes nothing you need to act on. Sume's MCP endpoint is POST-only and, per the server source, does not use a session id, so there is no server-side session to terminate.
n8n's line is from its release notes; Sume's behavior is from the MCP server source and docs, read 2026-10-01. I could not see from these sources what request n8n sends when it terminates, so I make no claim about it.
What did n8n change?
The 2.42.0 notes list under bug fixes: "MCP Client Node: Terminate session before closing the client (#39526)". Separately, the MCP Python SDK 2.2.0 notes say a client DELETE frees its session immediately; that is a different project, shown here only as context for why clients clean up.
How does Sume's endpoint behave?
| Item | Value |
|---|---|
Endpoint info methods | ["POST"] |
GET /mcp | 405 with allow: POST |
| Tool surface | Selected public API capabilities wrapped as tools |
| Write and paid tools | idempotency_key required |
Will a cleanup request cause an error in my workflow?
If a client's cleanup step is a non-POST request, expect an error response from Sume: a GET returns 405 with allow: POST, and this post did not test other methods. A well-behaved client treats that as harmless at shutdown. If your workflow fails at the end, check whether the failing request is the cleanup or an earlier tool call before changing anything.
What should I do in n8n?
Keep the setup from n8n MCP Client Tool with Sume: the URL https://mcp.sume.com/mcp and one credential header. Since a paid create can be retried by a workflow, pass a stable idempotency_key and read job state with the returned job id instead of re-running the create. Session cleanup cannot cancel a job that Sume already accepted.
Sources
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