And if your running windows 10 make sure you launch both Steam and Uplay as Run As ADMINISTRATOR
this game was shipped well before windows 10 did ...and yes you may need to take that extra step to run the game
this games engine was created years before windows 10 shipped and that change may needed to allow the game to write any save files and or configuration files , windows 10 may handle file security \ permissions in a different way, then previous operating systems did.
if you have a problem... try this
right click on the games .exe file
select the compatability tab
check the box that says run as Administrator
set it to run in a windows 7 compatabilty mode
you can also run the windows 10 compatablilty trouble shooter from that same window
I'm getting the exact same thing now. Was fine two days ago when I played some GR Wildlands. Did not use the PC at all yesterday, and tonight I get this error with every attempt. Nothing has changed since I played last, no ports have been adjusted on my PC nor within the router, my rig hasn't even been powered on since I last played.