In this tutorial we’ll install the Debian Linux 9 (squeeze), Apache 2 with mpm-itk (to run each web as a isolated user),...
How to upgrade from wheezy to jessie
Ástþór IP1. Update all packages currently installed to the latest wheezy versions
apt-get update
apt-get upgrade
2. Replace all occurrences of wheezy with jessie in the apt sources file (pico /etc/apt/sources.list). Here’s an example of what the file could look like after the change:
deb http://ftp.debian.org/debian/ jessie main contrib non-free
deb http://security.debian.org/ jessie/updates main contrib non-free
3. Update apt repository
apt-get update
4. Upgrade all packages
apt-get dist-upgrade
5. Restart the system
reboot
6. Verify that the system is updated to Debian Linux 8 (Jessie)
cat /etc/debian_version
It should read version 8.0.0 or greater