Now I think about it harder, I suppose I should mention a few more details.
On the test VM I spun up for the reproducer, I was doing all of this by logging in on a text virtual console. On the real machine where I had this problem originally, I'm doing remote working by SSHing in, running vncserver to start up the X session, and then connecting a VNC client to it. So, in both cases, the user-level systemd process is already running *before* I set up the new X display. I wouldn't be surprised if that was a key part of the problem: if you logged in on a display other than :0 via a normal display manager, it might well have set DISPLAY before even starting "systemd --user", and then everything might work. (But I haven't tried it.) Also, when I say "vncserver", that's the one from the "vnc4server" package. (I think that is probably not critical to the behaviour, but just in case.) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1898858 Title: xfce4-notifyd fails to start on displays other than :0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xfce4-notifyd/+bug/1898858/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs