KiCAD: Adding a label to schematic produces error in Pcbnew
The error is saying that your sw1 in your schematic has 4 pins (named 1, 2, 3, 4), but the footprint connected to that switch only has 2 distinct pads (only 1 and 2, could be spread out to more pads with the same name). Thus it cannot connect the two nets that are left. Try editing the footprint association, footprint or schematic so that it reflects your real-world design. (And make sure the footprint has the same amount of pins/pads as the symbol in your schematics.)