Diagnosis
A clog in the drain system is the first place to look. Food debris gets past the filter and blocks the drain hose or the air gap/garbage disposal connection.
How to Fix It
1) Start by cleaning the filter assembly in the bottom of the tub. Twist it counter-clockwise and lift it out. Rinse it thoroughly under hot water. 2) Look down into the now-open drain sump. Use a cup to remove any standing water, then check for large debris like pits or glass fragments. 3) Next, check the drain hose connection under the sink. Ensure it's looped up high (creating a high loop) before connecting to the disposal or drain pipe, and that it's not kinked.
If That Didn't Work
The drain pump itself might be jammed or failed. You can sometimes feel for an obstruction by accessing the pump (usually behind the lower kick plate), but this is a more involved repair.
Heads Up
If your dishwasher drains into a garbage disposal, always run the disposal and flush it with water after you scrape plates. The dishwasher drain port in the disposal can easily clog.