This question already has an answer here:

sudo: /etc/sudoers is world writable
sudo: no valid sudoers sources found, quitting
sudo: unable to initialize policy plugin

I was installing a font by using this command

sudo gnome-font-viewer /home/user-15/Downloads/aclonica/Aclonica.ttf

enter image description here

I used this before and it worked fine but now it is not working, I'm not able to install any font.

marked as duplicate by Rinzwind command-line Aug 20 '18 at 7:04

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  1. Boot up an Ubuntu live distro (via USB or CD).
  2. Mount your root file system. (let's say your root file system was mounted to /mnt)
  3. Execute sudo chmod o-w /mnt/etc/sudoers.
  • chmod: changing permissions of '/etc/sudoers': Operation not permitted – Tarun Narula Feb 24 '17 at 7:39
  • From the Ubuntu live CD you need to be root. Added sudo to my answer. – Sam Gleske Feb 24 '17 at 16:28

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