After upgrading from Ubuntu MATE 16.04 to 18.04, I can no longer get the network applet in the notification area.
This answer shows how I solved this in 15.04, and this solution survived the upgrades to 15.10 and 16.04, IIRC without any need for further intervention.
On 18.04 this no longer works:
~/.config/autostart/nm-applet.desktopwas no longer there, so I copied it back from
/etc/xdg/autostart/. The edits described in the original answer no longer apply, so I left the file unchanged. Even after login, the applet does not come back.
- When I try to launch
nm-appletmanually from the command line, it just gives me the message
Gtk-Message: 13:48:39.885: Failed to load module "topmenu-gtk-module", then exits and no network applet is ever displayed.
- The notification area, as indicated in this answer, is active—I see the volume applet.
- If it matters, I have the Traditional panel layout.
Additional information: on another computer (also upgraded to 18.04 from 16.04 but using the Familiar layout) the applet is still there.