[BUG]

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When the MCP server restarts (new container = new process), the old session ID is gone. Claude Code keeps trying with the
stale session ID and gets "Session not found" — but it doesn't attempt to re-initialize a new session. It just fails.

What Should Happen?

That's a bug in Claude Code's MCP client — it should detect a dead session and reconnect automatically.
workaround => exit claude code and back /resume session

Error Messages/Logs

Error: Streamable HTTP error: Error POSTing to endpoint: {"jsonrpc":"2.0","id":"server-error","error":{"code":-32600,"message":"Session
     not found"}}

Steps to Reproduce

rebuild your mcp server => claude wont work any more

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.56 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_