Guide to Fix Bad Day Crash
To fix the Bad Day crash bug, you need to put all your Hell’s Rangers gear and any legendaries you have into your stash until you receive the rewards from the mission. After you complete the quest and grab all your prizes, you can then safely put all the stuff you set aside back into your inventory. This is an official workaround recommended by Square Enix until the developers manage to patch the glitch out.
The bug itself and its cause are well-known to the creators, so don’t worry, it’s on the docket. As the devs put it: “We are aware of a bug that can cause a crash when receiving the rewards for the sidequest “A Bad Day”. This crash appears to only occur if you have the Hell’s Rangers equipment in your inventory.” Therefore, the Bad Day Crash Bug Fix is to “place the Hell’s Rangers items (and any legendaries) in your stash until you have received the side quest rewards.”