Must we make up the day we broke our fast on the thirtieth of Ramadan, after the announcement of an error in sighting the Shawwal crescent?

If you have broken your fast on this day, relying on a legitimate sighting in your country or in neighboring countries that share the same moonrise point with you, then you are not required to fast another day. The month may indeed be twenty-nine days, and the criterion is the sighting by the naked eye.