Add the paprika, salt, pepper, and brown sugar to a small bowl. Whisk to combine.
Rub the seasoning mixture on both sides of the ribs. Brush 1 1/4 cups of the barbecue sauce all over the ribs.
Place ribs into the slow cooker standing upright with the meaty side against the inside wall of the slow cooker. Pour the remaining barbecue sauce over the top. Pour the apple cider vinegar over everything.
Place lid on top and cook on LOW for 6-7 hours, or until the ribs are fall-apart tender. Do not open the slow cooker while cooking. Serve and enjoy!