January 1, 2015 is the feast of Mary, the Mother of God. We generally have Masses at 4:30 the previous day - in this case December 31 - and 9:00 and 11:00 on the actual day. BY FAR the largest attendance was at the 4:30 and all of us were expecting the Mass of January 1. Immediately before the Mass, the Pastor announced that we were changing the Mass to the Mass of December 31. Did the parishioners effectively miss a Holy Day of Obligation through no fault of their own? (By the way, I am in Montreal, Quebec, Canada)
Code of Canon Law:
Can. 1248 §1. A person who assists at a Mass celebrated anywhere in a Catholic rite either on the feast day itself or in the evening of the preceding day satisfies the obligation of participating in the Mass.
The canon does not say that the Mass must be the Mass of the feast day, it merely states that one must attend Mass. Therefore everyone who attended the 4:30 Mass did indeed fulfill their holy day obligation.