Package: x2goserver
Version: 4.0.1.20-1 
This is on Fedora 25, 4.8.16-300.fc25.x86_64 kernel. Certain users trigger the following errors in /var/log/messages when audio is not disabled:
pulseaudio[]: [pulseaudio] main.c: User-configured server at localhost:, refusing to start/autospawn.

Seems related to http://bugs.x2go.org/cgi-bin/bugreport.cgi?bug=161 and https://bugzilla.redhat.com/show_bug.cgi?id=830406 which is closed.