The most common cause of drainage failure is a neglected filter.
Most people stop at #1. If you want to truly know of clogs, you must go to #4.
Most modern dishwashers feature a multi-layer filter system designed to catch food particles before they enter the drain pump. This is the most common site for blockages.
: Make it a habit to clean your dishwasher filter at least once a month to prevent buildup and keep things flowing smoothly.
: Water takes an unusually long time to disappear or backs up into the sink. : Loud gurgling or thumping sounds during the drain phase. Dirty Dishes
Remove the filter and scrub it thoroughly with hot water, soap, and an old toothbrush.
If your filter has multiple parts (a fine mesh screen and a coarser plastic screen), separate them.