Whitelabel Error Page is the default error page in Spring Boot web app. It provide a more user-friently error page whenever there are any issues when user trying to access a apge.

Generally this is good to end users but we may watnt to see more error details during develop/debug stage. To show error stack trace, you can add following annotation in front of your SpringApplicaiton main class.

@SpringBootApplication(exclude = {ErrorMvcAutoConfiguration.class})
public class YourWebApplication {

After this change and restart your application, you’d see your familiar error page. :-)