How to fix this > attribute app:constraintBottom_toBottomOf not found

Thanks for the suggestions guys. I have managed to deal with the error by adding this line

implementation 'com.android.support.constraint:constraint-layout:1.1.3'

into my build.gradle(module.app) under dependencies

Again, thanks for everything

You should use app:layout_constraintBottom_toBottomOf only in ConstraintLayout. You can try to use inside of FrameLayout then android:gravity = "bottom" in your LinearLayout.