What invalidates wiping over the socks?

The nullifiers of wiping over the socks are: what necessitates ghusl (ritual bath for major impurity), removing the sock, the exposure of part of the foot according to the majority of scholars, and the expiration of the wiping period (one day and one night for a resident, and three days and nights for a traveler). If any of these nullifiers occur, the person must wash their feet when performing ablution, and then they can wipe over them again.