xfce4-power-manager does not open

Question

I recently changed my DE from Unity to XFCE. I really enjoyed it, but the power manager doesn't work. When I try to open it from the settings menu, I get the following error:

Unable to connect to Xfce Power Manager

Did not receive a reply. Possible causes include: 
the remote application did not send a reply, the message bus security policy
blocked the reply, the reply timeout expired, or the network connection was
broken.

When I try to run it from the command line, it simply does nothing. I found some other solutions where people said to try running xfce4-power-manager --no-daemon (here: xubuntu 13.10 xfce4-power-manager not working), but then I get the following messages:

(xfce4-power-manager:23973): xfce4-power-manager-WARNING **: could not map keysym 1008ffa8 to keycode


(xfce4-power-manager:23973): xfce4-power-manager-WARNING **: 'CheckAuthorization' failed with Action org.freedesktop.udisks.drive-set-spindown is not registered

And then the shell halts until I hit ctrl+c.

Then I read that this is a known bug and the best solution was to downgrade to a previous version of the power manager. I tried using aptitude for this, but it complained that every version I wanted did not exist, even if I was taking the version numbers from the xfce4-power-manager repository. The next thing I tried was to download the package and install it myself. But when I tried to configure, the script told me some libraries were missing, even though they are installed:

*** The required package libxfconf-0 was not found on your system.
*** Please install libxfconf-0 (atleast version 4.6.0) or adjust 
*** the PKG_CONFIG_PATH environment variable if you
*** installed the package in a nonstandard prefix so that
*** pkg-config is able to find it.

I was told that library is already pre-installed in Ubuntu.

Then I tried using the gnome-power-manager. Even though it is installed, when I try to run it from the command line, it says there is no such program. And it would also not appear in the XFCE settings menu, which I would like.

Solution 1

Updating instructions for Xubuntu 14.04.1

First remove the old launcher
sudo rm /etc/xdg/autostart/xfce4-power-manager.desktop

Then create a new one....
Settings Manager / System / Session and Startup
Choose tab Application Autostart

At the bottom click Add and enter the following:

Name: Xfce Power Manager (for example your name)
Description: Power manager startup
New command: xfce4-power-manager --no-daemon

Edited because the askubuntu interface is messing up CR/LF

Solution 2

@Eddie is on the right track in his answer here, but I recommend you should instead only:

Edit the file /etc/xdg/autostart/xfce4-power-manager.desktop to include the --no-daemon addition to the end of the xfce4-power-manager command, by doing the following:

sudo nano /etc/xdg/autostart/xfce4-power-manager.desktop
Now arrow down to the bottom of the file and replace this line:
Exec=xfce4-power-manager
with this line:
Exec=xfce4-power-manager --no-daemon

Use ctrl + x to exit nano, select 'Y' to save, then reboot and the power manager will now work from the settings menu.

Note: Tested and works at least in Ubuntu 14.04 LTS.