Typically, this error message is the result of just general connection difficulties somewhere between our servers and a player. Which unfortunately means there is usually nothing we can do about it. It usually goes away after a while.
Please eliminate possible problems on your end. For instance, try a wired connection if you're using a wireless one, shutdown other applications that use the net, etc.
Then open the Settings program in your Battleground Europe folder and choose a Connection instead of Use Best and try to login.
If that doesn't work, change the connection to use the other option. (This is choosing your path to our game servers). One might be better for you than the other (and is why we have two).
If this occurs on both connections and only after the most recent patch, please run a tracert to authdevng.playnet.com and post the results in a support ticket. To do this, open the cmd program (start menu and run, or google) and then type in tracert authdevng.playnet.com.