DIAGNOSIS Standing water post-cycle is a classic drain problem. The most common culprits are a clogged drain hose, a stuck drain pump, or a clogged air gap or garbage disposal connection if your dishwasher drains into one.
FIX Check the drain path first. If your dishwasher drains into a garbage disposal, make sure the knockout plug in the disposal inlet is removed. Then, run the disposal to clear any debris. Next, check the air gap on your sink (if you have one) for clogs. Finally, inspect the drain hose under the sink for kinks.
IF THAT DIDN'T WORK The issue is likely inside the dishwasher. The drain pump might be obstructed. You'll need to access it. After unplugging the machine, remove the filter as described earlier. You can sometimes see debris near the pump housing. You may need to disconnect the drain hose at the pump to check for a blockage.
HEADS UP Don't just run more cycles hoping it'll clear. Standing water will lead to smells and can cause the dishwasher to not fill properly on the next cycle, as it senses leftover water. Always disconnect power before poking around near the pump.