Basically, I solved the problem by installing the licensed version 3.0 and then applying patch 3.1. It seems to be working, I'll keep testing it) :D :p
Added after 27 minutes
Actually, I was wrong. The problem is related to the "240H" mod - opening new heroes and improving old ones. It's in the data folder. Can you advise me on how to fix it or get those heroes?
Is there a link to the "240H" mod?

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Неудачное планирование ведёт к неудаче ...
NCF - мод, добавляющий дополнительных существ в HeroesV 3.1