DIAGNOSIS Hard water scale and no detergent dissolving properly. The most common cause is a clogged or missing filter assembly letting food debris recirculate.
FIX Remove the lower rack. Twist the cylindrical filter assembly in the sump at the bottom counter-clockwise and lift it out. Take it apart per its design—usually a main filter, coarse filter, and fine mesh filter. Rinse all pieces under hot water. Scrub any debris from the sump area. Reassemble and lock it back in place.
IF THAT DIDN'T WORK You have very hard water and the built-in softener is out of salt. Open the detergent dispenser. The rinse aid compartment is on the door. The larger, covered compartment behind it is for liquid jet dry or dry salt. Fill it with dishwasher water softening salt, not table salt.
HEADS UP Never use powdered detergent in the main cup if you have the built-in softener. It can clump and block the system. Use pods or liquid.