The game won't start since the new launcher.

When the new version has came out I had Windows 10 and firstly the launcher didn't want to update, then it has finally updated, but when I start the game it blinks and a text come up, "An unexpected issue occurred and the game has crashed. We're sorry for the incovenience.". Please can somebody help me ASAP.
And I have reinstall the game and also I changed from win 10 to win 8.1.
Thx for you reply