The issue suggests adding ButterKnife.unbind(unbinder) in the onDestroyView callback of BaseFragment.java. The file is located at app/src/main/java/com/github/pedrovgs/effectiveandroidui/ui/fragment/BaseFragment.java. Currently, the unbind call is missing, which could cause memory leaks or issues with view binding after the fragment's view is destroyed. The fix involves adding a single line after the super call in onDestroyView, using the Unbinder object that is likely already returned from ButterKnife.bind().
ButterKnife Fragment unbinding · pedrovgs/EffectiveAndroidUI#26 | Good First Issue