Following [this tutorial](https://github.com/socketio/socket.io-website/issues/url) leads to a compilation error. A user named Goldjee wrote a fix and posted it in a [comment](https://github.com/socketio/socket.io/issues/3890#issuecomment-1400650737). All you need to do is change: ``` declare module "http" { interface IncomingMessage { session: Session & { authenticated: boolean } } } ``` to ``` declare module 'http' { interface IncomingMessage { cookieHolder?: string; session: Session & Partial<session.SessionData>; } } ```