Boss bug Vaal Oversoul

I was doing the last part of the quest Shadow of the Vaal where it is to kill the boss and he disappeared and I can't advance to act 3. My friend found him in the previous area before the boss and I killed him but the mission doesn't progress and I'm stuck


Edit:
problem resolve all you need to do is restar your console then wait like 10 minutes and talk to the npc then go back to de mission and the boss respawn