Source note · Model Context Protocol transports compared
In Streamable HTTP under MCP revision 2026-07-28, a server that processes the request body MUST reject a request whose mirrored header values are missing, malformed or do not match the body, returning HTTP 400 Bad Request with JSON-RPC error code -32020 (HeaderMismatch).
Checked 2026-09-30
- Vendor
- Model Context Protocol project
- Product
- MCP specification
- Subsystem
- request metadata
- Deployment
- remote-http
- Region
- not restricted
- Release range
- MCP revision 2026-07-28
- Checked
- 2026-09-30
Sources
- Model Context Protocol specification 2026-07-28, Streamable HTTP — Model Context Protocol project · tier 1 standards and regulators · section Request Metadata, subsection Server Validation
Cite this note
APA
WarmTransfer. (2026, September 30). Model Context Protocol transports compared: source note mcp-transport-differences-http-header-mismatch. WarmTransfer. https://warmtransfer.net/knowledge/claims/mcp-transport-differences-http-header-mismatch
BibTeX
@misc{warmtransfer-claim-mcp-transport-differences-http-header-mismatch,
title = {Model Context Protocol transports compared: source note mcp-transport-differences-http-header-mismatch},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/mcp-transport-differences-http-header-mismatch},
note = {Source note mcp-transport-differences-http-header-mismatch, checked 2026-09-30}
}