pkexec does not find any authentication agent

I have just re-installed the policykit packages, no change.
And I have verified that polkitd is running.

When I try to start
DISPLAY=:0.0 /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1
from a shell, I get this error:
(polkit-gnome-authentication-agent-1:18885): GLib-CRITICAL **: g_variant_new_string: assertion `string != NULL' failed

(polkit-gnome-authentication-agent-1:18885): polkit-gnome-1-WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

I have exactly the same problem on XUbuntu 12.04:

- OS: XUbuntu 12.04, all updates are installed
- boot from USB drive (real installation, no live system); memory is o.k.: 8 GB flash drive; 3,5 GB free space
- computer: IBM T43, standard equipped, no special features; runs fine on Ubuntu 10.04 since years
- usage of Xubuntu 12.04 was o.k. for a few days; problem with synaptic password window occurred "out of the blue"
- I come around this problem by starting synaptic in the terminal

Status changed to 'Confirmed' because the bug affects multiple users.

Maybe I'm posting in the wrong place, if so, thank you for telling it and guide me to the wright one. I have also a problem with synaptic and polkit when I launch it from the menu with synaptic-pkexec it gives me this error (seens Xubuntu 11.10):

(polkit-gnome-authentication-agent-1:8248): polkit-gnome-1-WARNING **: Unable to get a pixbuf for GTK_STOCK_DIALOG_AUTHENTICATION (gtk-dialog-authentication) at size 48

I'm on Xubuntu 12.04 LTS 64 bit and by every session (autologin + autostartx with mingetty and no DM) I got this error from polkit-agent:

(polkit-gnome-authentication-agent-1:8248): GLib-CRITICAL **: g_variant_new_string: assertion `string != NULL' failed

(polkit-gnome-authentication-agent-1:8248): polkit-gnome-1-WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

The workaround is to start synaptic in a terminal with gksudo synaptic and no error occur.

Looks like it's the same problem. Maybe you could add a bit bug heat if you add yourself to the list of affected persons (the green link right below the heading "This bug affects ...").

Done, thank you.

I'm getting the synaptic problem, no restart or shutdown buttons (greyed out) and no sound. Can anyone else check their ck-list-sessions output.
[code]

sidney@sidney:~$ ck-list-sessions
Session1:
 unix-user = '1000'
 realname = 'sidney'
 seat = 'Seat2'
 session-type = ''
 active = FALSE
 x11-display = ':0'
 x11-display-device = '/dev/tty7'
 display-device = ''
 remote-host-name = ''
 is-local = FALSE
[/code]
active=false and is-local=false. I'm pretty sure it has something to do with consolekit

Got the is-local to turn to TRUE by changing the last line in /etc/pam.d/common-session to turn off nox11 mode. But still having the same 3 problems.

Here is mine:

ck-list-sessions
Session1:
 unix-user = '1000'
 realname = 'xxxxxxxxxx'
 seat = 'Seat1'
 session-type = ''
 active = FALSE
 x11-display = ''
 x11-display-device = ''
 display-device = '/dev/tty1'
 remote-host-name = ''
 is-local = TRUE
 on-since = '2012-05-28T04:49:07.132882Z'
 login-session-id = '4294967295'
 idle-since-hint = '2012-05-28T04:49:37.789423Z'
Session2:
 unix-user = '1000'
 realname = 'xxxxxxxxxx'
 seat = 'Seat1'
 session-type = ''
 active = TRUE
 x11-display = ':0'
 x11-display-device = '/dev/tty3'
 display-device = '/dev/tty1'
 remote-host-name = ''
 is-local = TRUE
 on-since = '2012-05-28T04:49:08.179929Z'
 login-session-id = '4294967295'

I don't know why, but by you something is realy wrong.

removed xdm, all 3 problems solved and I'm getting the same ck-list-sessions output as @Guy

Nice! You are starting X without any dm now? Do you still have the polkit-agent errors?

I went through and removed all the gnome stuff that I could get away with:

Start-Date: 2012-05-28 03:27:46
Commandline: synaptic
Install: compiz-kde:amd64 (0.9.7.8-0ubuntu1, automatic), compizconfig-backend-kconfig:amd64 (0.9.2-0ubuntu1, automatic)
Remove: python-keyring:amd64 (0.7.1-1fakesync1), unity:amd64 (5.12-0ubuntu1), metacity:amd64 (2.34.1-1ubuntu11), ubuntu-docs:amd64 (12.04.5), gir1.2-ubuntuoneui-3.0:amd64 (3.0.0-0ubuntu1), tumbler:amd64 (0.1.24-0ubuntu1), system-config-printer-gnome:amd64 (1.3.8+20120201-0ubuntu8), libtumbler-1-0:amd64 (0.1.24-0ubuntu1), ubuntuone-client:amd64 (3.0.0-0ubuntu1), zenity:amd64 (3.4.0-0ubuntu4), libgnome-control-center1:amd64 (3.4.1-0ubuntu2), libgtk2-perl:amd64 (1.223-1build3), gnome-settings-daemon:amd64 (3.4.1-0ubuntu1.1), unity-scope-musicstores:amd64 (5.12.0-0ubuntu1), gnome-session-common:amd64 (3.2.1-0ubuntu8), python-launchpadlib:amd64 (1.9.12-1), indicator-applet:amd64 (0.5.0-0ubuntu1), python-gnomekeyring:amd64 (2.32.0+dfsg-1), usb-creator-gtk:amd64 (0.2.38), indicator-applet-complete:amd64 (0.5.0-0ubuntu1), gnome-control-center-data:amd64 (3.4.1-0ubuntu2), gnome-keyring:amd64 (3.2.2-2ubuntu4), libpango-perl:amd64 (1.222-1build1), rhythmbox-ubuntuone:amd64 (3.0.0-0ubuntu1), sessioninstaller:amd64 (0.20+bzr128-0ubuntu1), ubuntu-sso-client-gtk:amd64 (3.0.0-0ubuntu2), tumbler-common:amd64 (0.1.24-0ubuntu1), indicator-power:amd64 (2.0-0ubuntu1), libsyncdaemon-1.0-1:amd64 (3.0.0-0ubuntu1), compiz-gnome:amd64 (0.9.7.8-0ubuntu1), desktop-base:amd64 (6.0.7ubuntu1), python-gi-cairo:amd64 (3.2.2-1~precise), libglib-perl:amd64 (1.241-1), python-ubuntu-sso-client:amd64 (3.0.0-0ubuntu2), network-manager-pptp-gnome:amd64 (0.9.4.0-0ubuntu1), ubuntu-sso-client:amd64 (3.0.0-0ubuntu2), libubuntuoneui-3.0-1:amd64 (3.0.0-0ubuntu1), yelp:amd64 (3.4.1-0ubuntu1), indicator-session:amd64 (0.3.96-0ubuntu1), zenity-common:amd64 (3.4.0-0ubuntu4), indicator-datetime:amd64 (0.3.94-0ubuntu2), gnome-control-center:amd64 (3.4.1-0ubuntu2), python-apport:amd64 (2.0.1-0ubuntu7), gnome-user-guide:amd64 (3.4.1-1), gnome-online-accounts:amd64 (3.4.0-0ubuntu1), compiz:amd64 (0.9.7.8-0ubuntu1), libpam-gnome-keyring:amd64 (3.2.2-2ubuntu4), python-gconf:amd64 (2.28.1+dfsg-1)
End-Date: 2012-05-28 03:31:55

Start-Date: 2012-05-28 03:41:54
Commandline: synaptic
Remove: libyelp0:amd64 (3.4.1-0ubuntu1), libnm-gtk0:amd64 (0.9.4.1-0ubuntu2), libgoa-1.0-0:amd64 (3.4.0-0ubuntu1), evolution-data-server:amd64 (3.2.3-0ubuntu7), libgoa-1.0-common:amd64 (3.4.0-0ubuntu1)
End-Date: 2012-05-28 03:41:59

Start-Date: 2012-05-28 03:49:02
Commandline: synaptic
Install: polkit-kde-1:amd64 (0.99.0-3ubuntu5, automatic)
Remove: policykit-1-gnome:amd64 (0.105-1ubuntu3), jockey-gtk:amd64 (0.9.7-0ubuntu7)
End-Date: 2012-05-28 03:49:13

With xdm installed, my /var/log/ConsoleKit/history entry looks like:

1338187484.617 type=SEAT_SESSION_REMOVED : seat-id='Seat1' session-id='Session1' session-type='' session-x11-display='' session-x11-display-device='' session-display-device='/dev/tty1' session-remote-host-name='' session-is-local=TRUE session-unix-user=1000 session-creation-time='2012-05-28T06:34:47.893356Z'
1338187484.628 type=SEAT_ACTIVE_SESSION_CHANGE...

It has turned out that the problem affects more components than I originally noticed:

When I try to configure system time / date in XFCE (also needed for selecting the appropriate NTP server), the dialog starts up locked and there is an "unlock" button. This button is also non-functional, probably due to the policykit problem.

Although I have seen some people finding workarounds, I think they aren't practicable. In the german ubuntu-users forum I have already got some feedback that the problem affects more and more users in between. And for every one, it comes out of the blue.
As this affects the system configuration and setup utilities, I consider it to be more important than the bug heat may indicate, but the bug status gives me the impression no one is actually working on it. I would like to kindly ask if there are any plans for this bug ...

After the last update to policykit-1-gnome 0105-1ubuntu3.1, nothing better. Concerning bugs around policykit-1-gnome, I hoppened a bug report, if more users are affected by the xsession-errors mentionned in #6, please let it know here too:

https://bugs.launchpad.net/ubuntu/+source/policykit-1-gnome/+bug/1000679

I have found the solution by happenstance:

(I am using XFCE in German, so maybe the wording I describe here is not 100% accurate)
In the XFCE settings menu -> Session management -> Automatically started applications, there is an Item "Policykit Authentication Agent".
This was unchecked. Re-check, reboot (probably logout and login is sufficient), and it is back working.

But: I am absolutely sure I did not remove the check. On one of the affected computers, I have never been in this dialog before.

That didn't help me...

I'm seeing the same thing in Xubuntu 14.04: pkexec works in text mode, but not GUI mode. If I run it with the --disable-internal-agent flag, it raises "Error executing command as another user: No authentication agent found." polkitd is running, as is polkit-gnome-authentication-agent-1.

This is a fresh install. This wasn't a problem in Xubuntu 12.10. I have installed some gnome-related packages in order to compile various programs. "Policykit Authentication Agent" in Session & Startup in the settings is enabled.

I have an unsubstantiated hunch that Bug #1314782 (multimedia keys don't work when xfce4-volumed is run in daemon mode) is related. Something to do with a dbus race condition.

It renders essential functionality of the package (or a dependent one) broken.

By the way, I find this is a transient issue. It went away after a reboot, but perhaps it'll come back after enough suspend/resume cycles, or on some subsequent reboot. Again, smells like a race condition.

On the advice of AlbertoSalvia Novella , I've submitted a new bug report against dbus with links to all the bugs (in my install of Xubuntu 14.04) that I vaguely suspect are related to one another:

Bug #1347272 (DBus communication problems affecting multiple packages)

Hi,

Just to say that it's steel the same after an upgrade 12.04.4 > 14.04.1 :

(polkit-gnome-authentication-agent-1:1810): GLib-CRITICAL **: g_variant_new_string: assertion 'string != NULL' failed

(polkit-gnome-authentication-agent-1:1810): polkit-gnome-1-WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files

Sorry if it's the wrong place to comment.

Still present in 14.04.2, will this buggy stuff ever be solved ?

Marcus Naeher has the solution in #17 above

For LXDE it is true as well that the PolicyKit Autostart has been unchecked by default in the latest version of Ubuntu/Lubuntu If you check this box and restart, Synaptic package manager will start from the launchpad menu and will ask for Authentication and all is well. Here is his answer quoted below:

"I have found the solution by happenstance:

(I am using XFCE in German, so maybe the wording I describe here is not 100% accurate)
In the XFCE settings menu -> Session management -> Automatically started applications, there is an Item "Policykit Authentication Agent".
This was unchecked. Re-check, reboot (probably logout and login is sufficient), and it is back working.

But: I am absolutely sure I did not remove the check. On one of the affected computers, I have never been in this dialog before."

This looks like the problem I have in Lubuntu 18.04 (but only in systems upgraded from 16.04 - new installs seem fine).

But I can't find the magic "Policykit Authentication Agent" tickbox in Lubuntu: where is it hiding?

Found the answer - I needed to install lxsession-edit, and that gives me the "Policykit Authentication Agent" tickbox. Now all is well.

One oddity though: on a fresh install of Lubuntu 18.04, everything works as expected - yet the Policykit Authentication Agent box is unchecked... Can anyone explain?