This error, I came across myself today. And I didn't find much for solutions when searching the various search engines.
No protocol specified
E: [pulseaudio] client-conf-x11.c: xcb_connection_has_error() returned true
I previous did not have this issue. Google hinted at an X display open type error. And then I recalled that I was trying to run pulseaudio as a user other than the one who started X. And xhost to the rescue.
As the user who started X, iceweasel (the user who did NOT start X) in this case.
$ xhost local:iceweasel
And the issue went away (again). I use startx to start X in my case.