Transaction was marked for rollback only; cannot commit

아래와 같은 에러가 발생해서 찾는 중

org.springframework.orm.jpa.JpaSystemException: Transaction was marked for rollback only; cannot commit; nested exception is org.hibernate.TransactionException: Transaction was marked for rollback only; cannot commit

먼 소리인지 눈에도 안들어 오는데 어떻게 해야하려나.. ㅠㅠ

[링크 : http://woowabros.github.io/experience/2019/01/29/exception-in-transaction.html]