The back-end Error -1 caused by annotation December 17, 2023 by Billy Wright-Brown No Comments SpringBoot novices need to be careful when it comes to annotations @Configuration @EnableSwagger2 1. The SpringBoot project is compiled as follows: Localhost: port number /swagger-ui.html#/ API 3. Add the above note after finding the reason: 4. After compiling, the browser loads the page: