What are the common issues and troubleshooting tips for a f-21 error on a Kenmore washer?

The common issues for a F-21 error on a Kenmore washer are clogged drain pump or hose, excessive suds, or a faulty drain pump. Troubleshooting tips include checking and clearing the drain pump and hose, reducing the amount of detergent used, and ensuring proper installation of the drain pump.