Must one complete fasting a day on which one practiced masturbation while fasting, and is it necessary to make up for this day?

Masturbation is forbidden (haram). Whoever commits it must perform sincere repentance. The fast of one who masturbates in Ramadan is broken if ejaculation occurs, and they are required to make up that day, unless they were ignorant of its prohibition, in which case their fast is valid according to the relied-upon opinion, though making up the day is more cautious.