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The biggest MCP revision since launch drops . Sessions are gone, sticky routing is gone, and three core features are on a deprecation clock. Here’s what every engineer building or maintaining an MCP server needs to know right now. #
You’re mid-sprint on a remote MCP server. You’ve just gotten sticky sessions working reliably across three instances using a shared Redis session store, your gateway is doing deep packet inspection to route Mcp-Session-Id
headers, and your deployment pipeline finally feels stable. Then you read the release candidate announcement and realize the ground just shifted under you.
The release candidate for the next Model Context Protocol specification is now available, delivering a stateless protocol core, an Extensions framework, Tasks, MCP Apps, authorization hardening, and a formal deprecation policy. The RC was locked on May 21, 2026, with the final spec scheduled for July 28, 2026.
This is not a minor version bump. Six material changes arrive simultaneously. If you run a production MCP server, you need a migration plan. If you’re starting a new one, build against the new model from…