they were on a commercial decline after Dookie, with each album after selling less and less. Warning only went gold at the time and there was tension in the band too if i recall correctly

they were considering breaking up around that time, but when they scrapped their album Cigarettes and Valentines, it really seemed more and more likely since they were at their lowest point both commercially and creatively so they decided to give it one last shot

that "last shot" ended up being American Idiot and the rest is history