To troubleshoot CORS issues, ensure your CORS middleware is configured correctly. Check that allowed origins, methods, and headers are specified correctly in your CORS settings.

Cross-Origin Resource Sharing (CORS) issues can prevent your Node.js application from interacting with resources hosted on different domains, leading to frustrating user experiences. To troubleshoot CORS problems, start by ensuring that your CORS middleware is configured correctly. If you’re using the popular cors package, verify that the origin, methods, and allowedHeaders options are set appropriately for your application’s requirements. For example, to allow requests from a specific domain, your configuration might look like this: app.use(cors({ origin: 'https://yourdomain.com' }));. Additionally, inspect the network requests in the browser's developer tools to view the error messages related to CORS, which can provide clues about what’s going wrong. Ensure that your server is sending the appropriate CORS headers in the response; missing headers can trigger CORS errors. If your application needs to support preflight requests (usually for PUT, DELETE, or requests with custom headers), ensure that your server handles OPTIONS requests and responds with the necessary CORS headers. By systematically checking these configurations and logs, you can effectively troubleshoot and resolve CORS-related issues.