nm-applet does not work Ubuntu 14.04

The network manager nm-applet has disappeared from the unity panel of my Ubuntu 14.04. When I try to run it from the commas line, I receive an error:

$ nm-applet
nm-applet-Message: using fallback from indicator to GtkStatusIcon

(nm-applet:6409): nm-applet-WARNING **: Could not find ShellVersion property on org.gnome.Shell after 5 tries

I do not know if it is directly related but ever since this, running System Settings-> Network does not display 'Mobile Broadband' even though the datacard is connected to the system. The datacard does not work any more.

EDIT: The following command as suggested by user 'mkayaalp' also gives an error:

$ nm-applet --shell-debug
nm-applet-Message: using fallback from indicator to GtkStatusIcon

(nm-applet:6848): nm-applet-WARNING **: Could not find ShellVersion property on org.gnome.Shell after 5 tries
nm-applet-Message: PID 0 (we are 6848) sent signal 2, shutting down...

(nm-applet:6848): GLib-CRITICAL **: Source ID 107 was not found when attempting to remove it

EDIT2: The problem of the icon for nm-applet not appearing on the unity panel is not unique to it. This problem also persists for 'Psensors' even though in options it is set to show on the unity panel.

P.S.: Searching on google and on askubuntu.com mainly brings up results regarding Lubuntu 14.04.

I'm afraid both messages look unrelated to your problem with Mobile Broadband connection.

nm-applet-Message: using fallback from indicator to GtkStatusIcon

simply means that a Gnome Panel was not found and it is using the status icon instead.

nm-applet-WARNING **: Could not find ShellVersion property on org.gnome.Shell after 5 tries

This message means that it tried to get the version of the Gnome Shell from DBus but failed for 5 attempts. On my system, there is no org.gnome.Shell service. But you apparently have and there is something wrong with it.

One thing you might want to try is running it as:

nm-applet --shell-debug

This should remove that second message, but I doubt it will resolve the broadband issue.

EDIT: I should mention that both these messages are not errors.

The following means that SIGINT was delivered and applet is exiting, which is what happens when you hit Ctrl+C in the terminal.

nm-applet-Message: PID 0 (we are 6848) sent signal 2, shutting down...

For next message, see this bug. It is GLib warning and not an error. nm-applet gives the same messages on my system (except for the dbus related message) and it works.

(nm-applet:6848): GLib-CRITICAL **: Source ID 107 was not found when attempting to remove it

Since you say the same thing goes for psensors, I am convinced that your problem is not nm-applet. It looks like your systray is missing. Try to run the following minimal python script for creating a status icon and see if anything shows up:

#!/usr/bin/env python
import pygtk
import gtk

i = gtk.StatusIcon()
i.set_from_stock(gtk.STOCK_INFO)
i.set_visible(True)
gtk.main()

Put this in a file and name it test.py. Execute chmod +x test.py and ./test.py. You might need to install python-gtk package, if not installed.

nm-applet disappeared from the Unity menu bar on a recent install of Ubuntu 14.04.1 LTS. This may have happened after an apt-get upgrade and a reboot.

The solution that worked for me was mentioned in the comments of another post.

Some people resolved similar issues by installing/reinstalling libappindicator. I guess Unity moved from status icons to indicators. – mkayaalp Aug 16 '14 at 18:35

Wow, the solution was the one buried in the comments by @mkayaalp. What I did was to run: 'sudo apt-get install --reinstall libappindicator3-1' and 'sudo apt-get install --reinstall libappindicator1'. Then restart. – noisygecko Jan 8 at 16:25

Since it worked for me, I thought I would make a separate answer for it. I ran the below:

sudo apt-get install --reinstall libappindicator3-1 libappindicator1

Then I rebooted. It may be that only the first package re-installation is necessary.

What fixed the issue here (Mint 17, compatible with Ubuntu 14.04) was:

sudo apt-get install --reinstall network-manager

sudo apt-get install --reinstall network-manager-gnome

sudo service dbus restart

followed by a logout and then a login. In fact, many other notification area indicators were missing (not only nm-applet), and this fixed them all.