Developers are lousy at maintenance and preparing for big events. They learn nothing from the JP version and all its problems still make it to the global version. 6 hours of unscheduled maintenance once the 2nd anniversary rolled out. Same thing apparently happened on the JP version during the 2 year anniversary and they shat the bed and let it happen again on global.
MicLemon27 about DRAGON BALL Z DOKKAN BATTLE, v3.1.2