I was having the same symptoms on my laptop (first, on debian stretch and then ubuntu 16.04 LTS).
I had neither installed flatpak nor dbus-user-session, and the gnome-keyring-daemon proposed workaround fixes didn't work for me.
I eventually found that it came from a CUPS configuration file (/etc/cups/client.conf), which was targeting an unreachable cups server.
I don't really get how a cups configuration would interfere with user functions, but it clearly did for me.
I was having the same symptoms on my laptop (first, on debian stretch and then ubuntu 16.04 LTS). daemon proposed workaround fixes didn't work for me.
I had neither installed flatpak nor dbus-user-session, and the gnome-keyring-
I eventually found that it came from a CUPS configuration file (/etc/cups/ client. conf), which was targeting an unreachable cups server.
I don't really get how a cups configuration would interfere with user functions, but it clearly did for me.