Posts Tagged ‘authentication’

If you’ve upgraded your Ubuntu system only to find you don’t have permission to do pretty much anything, as I did after upgrading to 13.10, it can be pretty annoying even for an advanced user, and downright scary for a novice. The symptoms are pretty obvious, as when you go to install updates, all you get is an error message saying “This operation cannot continue since proper authorization was not provided“. And using the Shutdown button seems to do nothing, and even using a terminal command to power off might see the shutdown process halt half-way through, forcing you to use the PC’s power button.

On top of that, even mounting removable drives (or other partitions on your internal drive) ends in being told you can’t, and even trying to play a DVD ends with “Unable to access “DVDVIDEO”. Not authorized to perform operation.

While there are ways around all of these situations for more advanced users, those less experienced with Ubuntu/Linux would find it all quite daunting, and pretty much look at their system as unusable. And one shouldn’t have to go through the bother of manually mounting drives through the terminal, or invoking the Software Updater as superuser, or any other thing we usually take for granted.

Luckily, the fix – which involves PAM (Pluggable Authentication Modules) – is actually quite simple, and should have everything back to normal in no time.

In a terminal, enter the following command to edit the PAM authentication file for the LightDM display manager:

gksu gedit /etc/pam.d/lightdm

Under the first line “#%PAM-1.0” paste the following 2 lines:

session required pam_loginuid.so
session required pam_systemd.so

Save and exit the file, then log out and back in again, and all should now be fine (you shouldn’t need to reboot).


Another method, which fixed the problem for some (but not in my case, and many others) is to run:

sudo pam-auth-update --force

This opens PAM‘s config within the terminal, at which you either check or uncheck items, or just hit Tab to go to OK, and hit Enter.


If need be, like you have GDM installed and it is interfering with LightDM, run dpkg-reconfigure gdm and select lightdm (you may need to reboot).


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