Myself and many others in my guild and discord are experiencing the same problem:
Having logged out in Stormwind, we are unable to log back in. Immediately upon zoning in, the message “You have been disconnected from the server. (WOW51900319)” is displayed.
Attempting to reconnect and log in again results in the same thing: precisely one frame of world animation, no opportunity for input, and disconnection.
This has also happened a number of times without logging out - simply being in Stormwind is sufficient to trigger the disconnection.
Would appreciate this being fixed ASAP - Thanks