Mysterious 90001 into 5006 Error combo

[X89K1]

So a problem I've seen sometimes is, typically when visiting worlds, but in other conditions sometimes as well, the game will freeze and then instantly disconnect with a 90001 error. When trying to re-log, the game gives a 5006 error and kicks to desktop.

Using PingPlotter, I identified no packet loss going on at the time of the disconnect, nor any other signs of the internet going out for any given length of time. Is there a known cause to this specific error combo above? And if so, how is it prevented?
(Edit: Fixed transferring to visiting. So there's no confusion between World Visit and actually transferring a character to a new home world.)