How can I troubleshoot a 403 error related to CORS in my Spring Boot application when using Postman?

First, verify your CORS configuration in your Spring Boot application (using `@CrossOrigin` annotation or `CorsRegistry`). Ensure the `allowedOrigins` include the origin from which Postman is sending requests (often `*` for testing, but should be restricted in production). Check browser developer tools for specific CORS error messages. Also, confirm Postman's 'Origin' header is being sent correctly.