There's a couple of ways that an overflow can occur during a brew. First, make sure that when you start the brew, you are just pressing the button once (quickly). We've had some customers press the button for the 3 seconds to enter the "Tea/Hot Chocolate" mode that heats and dispenses the water all at once (resulting in an overflow). Second, it's important to use 14g (~3 Tablespoons) or less of coarser grind (medium / coarse to coarse) grind coffee. Putting too much coffee in can cover the temperature sensor and the fine grinds can clog the filter.
