To solve this issue what i did :
- Closed Battlenet
- Control + Alt + Del > Kill all Battlenet agent.exe
- Launch Battlenet again
- Before clicking on update > Change region to another one (i dit Europe to America)
- The Download will started
- If your download is not starting you must click on Pause (right side of the download bar) wait maybe 10 seconds and click again and your download will continue again.
- Don’t forget to change your region back when your game is downloaded.
Important : changing your region have no impact on the game because the game is multi Lang