I had the exact same thing as the OP happen to me 3 times last night. At least twice, it happened right after a teleport. The first time was about 5 seconds after using an aether node to return to camp after leve completion, the second, when attempting to enter a market ward from a city zone line. (I got the error immediately after the teleport animation, upon relogging I appeared in the ward I'd been trying to get to.) The third, I don't quite remember, I think I was just standing around waiting for my buddy to meet me in Adventurer's guild.
I've never seen this error or behavior before the most recent patch, I guess a lil' bug found its way in there or something.
As already noted, closing out the client fully and restarting lets you log right back in.