getHibernateFlushMode is not valid without active transaction;

HTTP Status 500 - getHibernateFlushMode is not valid without active transaction; nested exception is org.hibernate.HibernateException: getHibernateFlushMode is not valid without active transaction

如果你是以上异常，可以在hibernate核心配置文件中查看是否有以下配置

<property name="hibernate.current_session_context_class">thread</property>

如果有，请删除（具体原因有待了解）