As with all software, Vivado has a number of “features” which you will sometimes have to deal with. This page is to help with a number of commonly encountered issues you may need to understand.

Before implementing anything in this section remember that anytime you make a change to your verilog code the simulation needs to be rerun. Your code describes your circuit and if you change it you change the circuit you are simulating. Sometimes relaunching the simulation isn't sufficient and the old simulation needs to be closed by exiting out of the simulator.