A confession may be invalid if the priest does not have the faculties to absolve, or if it is outside a true situation of emergency or necessity. For example, if a priest is suspended or excommunicated and is still using his faculties, the confession would be invalid. However, I repeat, in cases of emergency, it would still be valid.
Another situation where a confession is invalid is when the priest does not use the correct formula of the sacrament, the prescribed words of the Church. This is similar to a priest using invalid words for the consecration of the Eucharist, which would also make it invalid.
Additionally, a confession is invalid if the priest has no intention of celebrating the sacrament as the Church intends. On the side of the penitent, if someone consciously avoids confessing all their mortal sins and deliberately withholds a mortal sin, the confession would be invalid. Similarly, if a penitent confesses a mortal sin but is not truly repentant or has no intention of stopping the sin, the confession would also be invalid. All of these elements can make a confession invalid.
Dear visitors of Gloria Dei and all who have already written or who will write a personal message to me. I am grateful for your attention, your kindness, for your spiritual support and especially for your sacrifices and prayers for me. God may reward you!