(Android Studio) Failure [INSTALL_FAILED_VERSION_DOWNGRADE]

Failure [INSTALL_FAILED_VERSION_DOWNGRADE]

You're trying to install apk with a lower versionCode that is already installed.

출처 : http://202psj.tistory.com/799

해결 : 기존 스마트폰에 설치되어있는 기존 앱 삭제 후 다시 실행