The trial court dismissed Valerie Britt’s complaint, finding that Britt failed to establish her standing. The trial court never reached the merits of this issue; instead, the court relied on the doctrine of res judicata raised by appellees in a motion to dismiss. The dismissal order is fatally defective because a defendant generally cannot raise the defense of res judicata for the first time in a motion to dismiss. See Byrd v. City of Niceville, 541 So.2d 696, 698 (Fla. 1st DCA 1989) (holding that “[t]he issue of res judicata is an affirmative defense, and affirmative defenses cannot be raised in a motion to dismiss unless the allegations of a prior pleading in the case demonstrate their existence”); Holley v. Universal Rental Props., Inc., 416 So.2d 861, 861 (Fla. 1st DCA 1982) (holding that ‘Tilt is settled law that where the defense *258of res judicata does not appear on the face of the pleading, it may not be raised on a motion to dismiss, but must be plead and proved as an affirmative defense”). No exception to the general rule applies here.

REVERSED and REMANDED for further proceedings.