How can I handle CORS errors for API requests made from a different port on the same domain?

CORS errors can still occur even if the domain is the same but the port is different (e.g., frontend on port 3000, backend API on port 5000). You need to explicitly allow the frontend's origin in your Node.js API's CORS configuration. For example: `app.use(cors({ origin: 'http://localhost:3000' }));`. This tells the API server that requests from `http://localhost:3000` are permitted.