The past few days don't seem to be the best ones for Blizzard. Massive connection issues occurred in the four online games World of Warcraft, Diablo 3, Starcraft 2 and Hearthstone, giving players enough time to complain about these in the official forums.
What exactly causes these problems is currently unknown to the general public, yet Blizzard claims that they are already working on the problem. Meanwhile, a temporary solution for Starcraft 2 and World of Warcraft has been announced: Logging out of the Battle.net application and starting the game manually using the game.exe is said to solve the problem. The other two titles are still not playable.
If you would like to be kept up to date, you can follow the Blizzard Customer Support on Twitter