This guide will also solve the errors such as
You cannot play/edit this mission, it is dependent on downloadable content that has been deleted.dayz_code, dayz_weapons, dayz_equip etc.’upon joining any DayZ server. : DayZ Troubleshooting
You installed the mod or the shortcut incorrectly. Make sure you add “-mod=@dayz” without quotes in the launch options and DayZ mod files are installed in the proper folder. By default: “C:\Program Files (x86)\Steam\steamapps\common\arma 2 operation arrowhead\@DayZ\Addons”
