Hello, this is GM Lulu.
Server maintenance was carried out to fix Guild War errors on May 31 (Sun).
The Fortress settings of the players who had an error in Guild War has been reset.
It may be a hassle, but please make sure to set up your squade in Guild War > Fortress Setup to proceed the 21st season Guild War.
Please check this notice and make sure that there is no inconvenience in proceeding the Guild War content.