Upgrade Debian Lenny to Squeeze

You need to first edit the sources used for the apt repo's:

nano /etc/apt/sources.list

Now replace existing (or comment out the existing just in case):

deb http://mirror.bytemark.co.uk/debian/ squeeze main non-free contrib
deb-src http://mirror.bytemark.co.uk/debian/ squeeze main non-free contrib
 
deb http://mirror.bytemark.co.uk/debian/ squeeze-updates main contrib non-free
deb-src http://mirror.bytemark.co.uk/debian/ squeeze-updates main contrib non-free
 
#deb http://software.virtualmin.com/gpl/debian/ virtualmin-squeeze main
#deb http://software.virtualmin.com/gpl/debian/ virtualmin-universal main
 
#deb http://packages.dotdeb.org stable all
#deb-src http://packages.dotdeb.org stable all

Now update the distribution:

sudo apt-get update
sudo apt-get install apt dpkg
sudo apt-get dist-upgrade

You should restart the server to make sure all is ok - pot luck my friends:

shutdown -r now

Reboot – hopefully all ok!