Re: Sims 4 PS4, cannot host a toddlers birthday party?
@K8eP1 I have the same problem sometimes. Unfortunately I haven't found a way around it other than just letting the sim age naturally or aging them up without throwing a party. So here's the best way, I think: Turn aging on, then turn the lifespan to the lowest setting it will go, or not depending on how quickly you want your toddler to age up. Since your sims are vampires, they won't age (if they are young adults), except for your toddler. Eventually you will get a notification saying "It will be (your sim)'s birthday in a few days". Then when a day or so passes, you'll get another saying "It is (your sim)'s birthday today!" This is the day when you can throw them a party. After they've aged up, set the aging back to whatever you want.
That's how I've been doing it. I hope it works for you!