Error: Could not stat() command file ‘/var/lib/nagios3/rw/nagios.cmd’!

While working on Nagios Server in Ubuntu 12.04 LTS,I was setting external command and stuck with this error message.

To solve the problem follow these commands

sudo /etc/init.d/nagios3 stop
sudo dpkg-statoverride --update --add nagios www-data 2710 /var/lib/nagios3/rw
sudo dpkg-statoverride --update --add nagios nagios 751 /var/lib/nagios3
sudo /etc/init.d/nagios3 start

Note: This error is actually a bug, for a reference this is a link https://lists.ubuntu.com/archives/ubuntu-server-bugs/2009-June/013748.html