If it is a frost free fridge, there must be some 1/2" pipe coming out of the back of the refrigerator that must be clogged. Follow the instructions to unclog the pipe . by taking out the plastic case of the top freezer
I had this problem recurring several times with a GE fridge I finally solved it by attaching an inverted L shape piece of 3/16" copper tubing into the drain hole, The longer side of the L has to be long enough to be placed 1-1/2 -2" inch inside the drain tube. The short end of the copper L tube, about 1-3/4" long I attached it firmly to the heating element that do the defrosting with a small screw clamp. It has not leaked ever since. The copper tube will get warm and melt any ice trying to enter the drain hole. It is a $5 fix ยท