I was geting this too and I disabled all my addons and it stopped. I have not yet narrowed down which one is the issue but EFT and Lazy Writ Crafter and the files needed to run them are fine cos I've been running those two for a bit now. It will be an addon that has not been updated for new patch yet causing it.

another maintenance , another Lost lobby connection Spam , come on ZoS , what is the deal , your Megaserver cant handle people logging into an online game???