기존에 설치된 앱이 있다면 삭제 후 재빌드하자.
터미널
BUILD FAILED in 37s
error Failed to install the app. Make sure you have the Android development environment set up: https://reactnative.dev/docs/environment-setup.
Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081
Unable to install /Users/project/android/app/build/outputs/apk/debug/app-debug.apk
com.android.ddmlib.InstallException: INSTALL_FAILED_VERSION_DOWNGRADE
해결방법
기존에 설치된 앱이 있다면 삭제 후 재빌드하자.