Getting this very frequently after getting kicked out the game and since this time I was at Tho'at, who was at 3% and I had just dropped my ultimate on her to finish her off when I got booted, it is particularly frustrating to be getting this annoying error message again and again while trying to log back in, knowing that by now my run will have been lost and I will have to start all over on what is already an annoyingly long daily quest to complete.

Can anyone help with what this stupid error actually means and how I can quickly resolve it next time it happens (probably at the rate it has been happening, later today)?