What is the ruling on the prayer led by an Imam who is not in a state of ablution if he remembers this during or after the prayer?

Whoever remembers the incident after the prayer should repeat their prayer. And whoever remembers it during the prayer should interrupt their prayer. If he is an Imam, he should appoint a successor who is fit for Imamate. It is a condition for the successor to have been following the Imam before his incident, even if he is a boy or performing a supererogatory prayer.