This another common problem for the new users for Linux. Anonymous change of permission of root or while experimenting we do run commands which results into some unexpected results.
we can observe this output while doing sudo su in linux mainly in ubuntu.
The solution lies in changing the permisions
Method 1: While booting hold on shift and from the recovery menu drop to the root shell and run the following commands
chown -R root:root /usr/bin/sudo
mount -ro remount,rw /
mount -ro remount,ro /
basically we are changing the owner and remounting to fix this error.
If this doesn,t work do opt the next method
Method 2 :pkexec chown root:root /usr/bin/sudo
pkexec chmod 4755 /usr/bin/sudo
and boot normally.
This will get you out of the effective uid error.