Is a makeup fast or an expiation required for one who broke their fast on the first day of Ramadan unknowingly, and should they complete the fast for that day?

If a Muslim breaks their fast on the first day of Ramadan without knowing that the month has begun, they must abstain from eating and drinking for the remainder of that day. According to the majority of scholars, they are required to make up that day, but no expiation (kaffarah) is obligatory upon them.