서버는 잘 도는데 add pet 등 만지니 에러가 찍힙니다

2020-05-24 23:16:01.332 ERROR 30384 --- [nio-8090-exec-8] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.RuntimeException: Expected: controller used to showcase what happens when an exception is thrown] with root cause

이런 에러가 찍히는데.. 구글링해보니 db관련 문제라고 하는데 어떻게 해결해야할까요? 감사합니다