In my project during react scheduler rendering there could be a change in a store from what I feed my scheduler. And by that point on some occasions this.parent.activeView is undefined, thus throwing startDate of undefined. I will open a PR with a if-return, but I guess it's better for you guys to check why activeView could be not set. I can't share my react code here, but I am setting literally currentView="Week" for the scheduler component + isSelected option on ViewDirective and it works well but sometimes the scheduler crashes, when there is refreshDataManager invocation before this.parent.activeView is set on scheduler component first time rendering.