I've setup successfully a tigervnc server. I've been able to successfully remotely log in the VNC session using a viewer desktop client or Apache Guacamole.
Now is the day after and the host computers have their screen locked. When I launch the VNC session, I see the locked screen. When I swipe the mouse or press "space", the login screen is stuck on "Authentification error" and you cannot do anything except reboot or hit "ESC". You cannot type in the login field. It is like the VNC session is trying to login multiple times per second.
In journalctl, I can see:
JS ERROR: Failed to open reauthentification channel: Gio.DBusError:org.freedesktop.DBUS.Error.AccessDenied: No session available
_reauthentificationChannelOpened@resource:///org/gnome/shell/gdm/util.js:352:34
wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22