Tom Clancy´s Ghost Recon: Wildlands Message Board  

I haven't finished downloading yet but try this.

Disable the game's anti-cheat system by launching it with the command -eac_launcher. To do so if launching the game through Uplay, right-click it -> click "View game details -> select "Properties" from the menu -> click "Add launch arguments" -> input -eac_launcher into the field; if you have the Steam version, right-click it -> click "Properties" -> click "Set launch options" -> input -eac_launcher into the field. Alternatively, if you're running either version via a desktop shortcut, you can achieve the same result by righting-click it -> clicking "Properties" and -> adding -eac_launcher to end of the target field, separating the two with a space.
Note: Disabling EAC will also completely disable the the multiplayer component.