Cause 1
If the drawer is not locked during operation.
Cause 2
If the drawer is not closed due to foreign substances getting stuck in the area around the drawer;
Solution
Open the drawer, check under the drawer, and remove any foreign objects that are keeping the drawer from closing all the way.
Thoroughly check all around the drawer area for a foreign object that is keeping the drawer from closing and locking in place properly. Smaller items like socks are sometimes dropped by customers by accident and cause the dE4 error to display.