# NousResearch/hermes-agent · Streamable HTTP MCP client connection and negotiation fixes

## Open now

- Nothing open on GitHub.

These issues and fixes address bugs in the Streamable HTTP MCP client: improving error messages to surface HTTP status, URL, and body on failures, and correcting protocol version negotiation during the handshake.

## TL;DR

- 3 member(s): 0 open issue(s), 1 closed issue(s), 0 open PR(s), 1 merged PR(s), 1 PR(s) closed without merging.
- A fix was merged to main in PR #114817. Verify it addresses your case.
- **Recommended:** read PR #114817 (and any competing PRs below) before filing. Confirm the merged change covers your symptom.

## Maintainer resolution verdict

- Internal-tracker verdict over this cluster's issue members: `resolved` · deciding PR(s): `pr-114817`. This is distinct from the fix status above. Weigh it yourself.

## How this cluster was grouped

- Link evidence (`STRUCTURAL_SPANNING`): every member is connected by structural evidence: shared changed files, or a closing/superseded reference.
- Pairwise link density `0.67`: the share of member pairs that carry a link, counting a structural link in full and a relevance-only link at 0.36. `1.00` means every pair is linked.

## Closed / duplicate issues

- #114350: \[Bug\]: Streamable HTTP MCP client fails against a server that negotiates a non-latest protocol version

## Prior & competing PRs

- **#114817: fix(mcp): Streamable HTTP connect failures name the HTTP status, URL and body behind "Server returned an error response" (#113359, #114350, salvage #113392)**. merged to main · fix tier `verified`
  - maintainer direction: category `merged`
  - files: `tests/tools/test_mcp_protocol_negotiation.py`, `tests/tools/test_mcp_sse_fallback.py`, `tools/mcp_tool.py`, `tools/mcp_tool_errors.py`, `tools/mcp_tool_transport.py`, `website/docs/user-guide/features/mcp.md`
- **#114381: fix(mcp): don't advertise an unnegotiated MCP-Protocol-Version on the streamable HTTP handshake**. closed without merge
  - maintainer direction: category `superseded_by_pr`; implication `superseded`; refs `#113392`

## Fix status

- Merged to main in PR #114817 (cited above). No release data is tracked. Verify downstream.
- Fix last verified (merged) `2026-09-18`.