No EntityManager with actual transaction available for current thread Exception on Spring

@Transactional(readOnly = false)
public interface FormRowRepository extends JpaRepository<FormRow, Long> {
    List<FormRow> findByForm(Form form);
    void deleteById(Long id);
    void deleteById(List<Long> ids);
}

References
https://stackoverflow.com/questions/10394857/how-to-use-transactional-with-spring-data