Filesystem MCP server fails to start when any allowed directory is unavailable

[smith-and-web]

Describe the bug
The @modelcontextprotocol/server-filesystem fails to start entirely when any of the configured allowed directories is unavailable (unmounted network volume, disconnected external drive, etc.).

To Reproduce

1. Configure filesystem MCP with multiple allowed directories, including a network mount
2. Disconnect/unmount the network volume
3. Restart Claude Desktop
4. Observe that filesystem MCP fails to start

Expected behavior

• Server should start successfully
• Log a warning about unavailable paths
• Serve the directories that ARE accessible
• Optionally retry unavailable paths periodically

Logs

Error accessing directory /Users/josh.smith/Projects: Error: ENOENT: no such file or directory, stat '/Users/josh.smith/Projects'
    at async Object.stat (node:internal/fs/promises:1040:18)
    at async file:///Users/josh.smith/.npm/_npx/a3241bba59c344f5/node_modules/@modelcontextprotocol/server-filesystem/dist/index.js:43:23
    at async Promise.all (index 1)
    at async file:///Users/josh.smith/.npm/_npx/a3241bba59c344f5/node_modules/@modelcontextprotocol/server-filesystem/dist/index.js:41:1 {
  errno: -2,
  code: 'ENOENT',
  syscall: 'stat',
  path: '/Users/josh.smith/Projects'
}
2026-01-19T17:51:52.024Z [filesystem] [info] Server transport closed { metadata: undefined }
2026-01-19T17:51:52.024Z [filesystem] [info] Client transport closed { metadata: undefined }
2026-01-19T17:51:52.024Z [filesystem] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. `console.error('...')` in JavaScript, `print('...', file=sys.stderr)` in python) and it will appear in this log. { metadata: undefined }
2026-01-19T17:51:52.024Z [filesystem] [error] Server disconnected. For troubleshooting guidance, please visit our [debugging documentation](https://modelcontextprotocol.io/docs/tools/debugging) { metadata: { context: 'connection', stack: undefined } }
2026-01-19T17:51:52.024Z [filesystem] [info] Client transport closed { metadata: undefined }
2026-01-19T17:51:58.217Z [filesystem] [info] Client transport closed { metadata: undefined }
2026-01-19T17:51:58.216Z [filesystem] [info] Shutting down server... { metadata: undefined }

Additional context
Environment:

OS: macOS 26.1
Claude Desktop: 1.0.3218
MCP Server: @modelcontextprotocol/server-filesystem (latest)

Impact:
This makes the filesystem MCP unreliable for any setup involving:

Network shares/NAS devices
External drives
Mounted volumes
Any path that might be temporarily unavailable