Start player does not exist on map

Thank you for your participation, I have already figured it out. After completing the tasks, I edited the "players" tab, which then changed the "MainHero" parameter. As soon as I reverted it (assigned a hero) and launched the map, alliances appeared (all players became allies), and the map refused to launch at all. Perhaps this simple rule will help someone else: "Don't change all the settings at once."