My code is like
class WaitForBid(WaitPage):
    wait_for_all_groups = True

    # @staticmethod
    def after_all_players_arrive(group: Group):
        subsession = group.subsession
        # Initialization
        if subsession.round_number == 1:
            ...
        ...
        players = group.get_players()
        ...
I didn't put "subsession" into after_all_players_arrive() and why did this problem happen? I also tried to change "group: Group" into "self" and the error would be like "missing an argument 'self'". My otree version is 5.11.4.

The oTree AI told me that the problem is from "wait_for_all_groups = True". It is right.