Root error report and solution

https://www.cnblogs.com/dpf-learn/p/7704958.html

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

This is a limitation made by Linux to ensure system security. The solution is to run the following two commands:

pkexec chmod 555 /etc/sudoers
pkexec chmod 555 /etc/sudoers.d/README

solution:

The permission of sudoers has been changed, just change it back.

pkexec chmod 0440 /etc/sudoers
pkexec chmod 555 /etc/sudoers.d/README

But the above method doesn't work 

sudo: /etc/sudoers.d can be written by anyone_/etc/sudoers.d/_lucky lures' blog - CSDN Blog

sudo su
# password
chown -R root:root /etc/sudoers.d
chmod u=rwx,g=rx,o=rx /etc/sudoers.d/
chmod u=r,g=r,o= /etc/sudoers.d/*
exit

success!