Upgrade to Debian Jessie
Only do this if you know what you are doing.
Backup your old sources.list
:
cp /etc/apt/sources.list{,.backup}
Replace all occurrences of wheezy
by jessie
, update the package list and run the upgrade:
sed -i "s/wheezy/jessie/g" /etc/apt/sources.list
aptitude update
aptitude dist-upgrade"