Due to a bug on my local sourcetree, owner and group of /etc and /root directories might be wrong.
Please check owner and group of /etc and /root directories.
ls -la /
Should look like this:
drwxr-xr-x 94 root root 4096 Feb 27 18:58 etc drwxr-x--- 13 root root 4096 Nov 27 16:35 root
If it doesn't, then please correct owner and group using following commands:
sudo chown root:root /etc sudo chown root:root /root