Remove the bottom dish rack and unscrew the cylindrical filter at the floor of the dishwasher. You will likely find a horror show of corn kernels, plastic labels, and slime. Clean it with a brush. Next, disconnect the rubber drain hose. Run a garden hose through it or use a long, flexible drain brush (a “plumber’s snake” for dishwashers).
Run your garbage disposal before starting the dishwasher, not after. And once a month, run a cycle with a cup of white vinegar on the top rack (no detergent) to keep the pipes slippery and clear.
Before you begin, cut the power to the dishwasher at the breaker box. Electricity and standing water are a dangerous mix.
If the filter is clear, run your garbage disposal (if you have one) with plenty of water. A clogged disposal often backs up into the dishwasher hose.