If I invoke epiphany from the terminal or from the gnome menu I don't get the 'dbus' error message. But when I click on a link to a bug report from update-manager, epiphany is invoked (because it is in the alternatives system as 'gnome-www-browser'). Here is the relevant info from '.xsession-errors':
(epiphany-browser:7149): GnomeUI-WARNING **: While connecting to session manager: Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed. ** (epiphany-browser:7149): WARNING **: Unable to connect to session bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. (epiphany-browser:7164): GnomeUI-WARNING **: While connecting to session manager: Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed. ** (epiphany-browser:7164): WARNING **: Unable to connect to session bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. (epiphany-browser:7244): GnomeUI-WARNING **: While connecting to session manager: Authentication Rejected, reason : None of the authentication protocols specified are supported and host-based authentication failed. ** (epiphany-browser:7244): WARNING **: Unable to connect to session bus: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]