XFCE is one of the most lightweight desktop environment among other Linux desktops, resource-friendly suitable for old PC/Computers. XFCE removed most of the non-essential elements such as glossy desktop design, animations, etc in terms of making it more resource-friendly. But the problem is, if you install XFCE on the top of another desktop environment (Such as installing XFCE desktop on Linux Mint Cinnamon environment), you will encounter this error due to the absence of XFCE meta-package.
If you are also not able to adjust your screen brightness due to this missing component follow these steps below to fix it.
1| Open your terminal and execute the following command...
sudo apt-get install xfce4-power-manager-plugins
2| Enter your password and press the
y key to continue (if asked)
3| Now, Right-click on the panel, Panel-> Add New Items...
4| From the "Add New Items" list, search for
Power Manager Plugin, select it then click on the Add button.
5| Now, you will see the
Power Manager icon appear on your panel, just click on that to begin adjusting your screen brightness.
Thanks for reading. Have a great day :)