/tiphat
Unfortunately, this update blocker has been an issue for a long while now, and while the resolution has been posted likewise in the forums, the error message first seen and resolution link is inaccurate (i.e. we know now how to clear the problem, but not why it happens). Just from August last year (and it appeared much earlier than that):
WowVoiceProxy.exe starts when you load a character in game, then is supposed to terminate when you log out. Because it doesn’t cleanly terminate 100% of the time, I’ve been able to get up to 4(!) instances of that exe (or the WowVoiceProxyT.exe on the PTR) running at the same time. I believe it happens on Classic as well (though I’d want to reconfirm that).
I tried to bring attention to it on the 8.3 PTR since October, but nope, no luck in getting it fixed.