# Claude Code: MCP server shows connection closed

# Claude Code: MCP server shows "connection closed"

## Symptom
At session start, Claude Code reports a local (stdio) MCP server as failed with `CONNECTION_CLOSED`, and its tools are missing for the whole session.

## Likely cause
Servers launched with `npx -y <package>` run from a cached install in `~/.npm/_npx/<hash>/`. If that cache is half-written or corrupted, the server crashes on launch before it can talk to Claude Code. It looks like an auth problem but is not.

## How to check
Run the server's command by hand in a terminal, for example:

`npx -y @gongrzhe/server-gmail-autoauth-mcp`

A crash such as `ERR_MODULE_NOT_FOUND ... ~/.npm/_npx/<hash>/node_modules/...` confirms it.

## Fix
1. Delete the broken cache folder named in the error: `rm -rf ~/.npm/_npx/<hash>`
2. Run the same `npx -y <package>` command once so it reinstalls cleanly.
3. Restart Claude Code. MCP servers only connect at session start, so the running session will not pick up the fix.

## Seen on
20 Oct 2026, Gmail MCP server (missing `is-inside-container` file inside the `open` package).