I run a production remote MCP server that generates invoice PDFs for agents and had to migrate it for the July 28th spec release--the largest revision since MCP launched: protocol sessions and the Mcp-Session-Id header are removed, new mcp-* headers become mandatory, error codes change, and sampling/logging/roots are deprecated.

This guide is the writeup I wish existed when I started. It shows what breaks, why, and the exact migration steps for each. The short version: if your server keys any state on session IDs, it breaks at the cutover. Move state into explicit handles passed as tool arguments.

My own server is the test bed. Everything in the guide is verified against a live deployment. Happy to answer migration questions.