Last night I updated the system to Debian Jessie. This did not go without a struggle. But we are online again.

Upgrade Debian Wheezy to Jessie safely

First make a complete backup of your system. I use rsync for this and put the backup on a remote vps.

rsync -uavzh --exclude='/mnt' --exclude='/proc' --exclude='/sys' --delete-after /  
                     user@server-ip-addr:/backup/gw-pd2lt

Make sure that your system is completely updated.

apt-get update

apt-get upgrade

apt-get dist-upgrade

Update the sources.list for Jessie

nano /etc/apt/sources.list

deb http://ftp.de.debian.org/debian/ jessie main contrib non-free
deb-src http://ftp.de.debian.org/debian/ jessie main contrib non-free


deb http://httpredir.debian.org/debian jessie-updates main contrib non-free
deb-src http://httpredir.debian.org/debian jessie-updates main contrib non-free


deb http://security.debian.org/ jessie/updates main contrib non-free
deb-src http://security.debian.org/ jessie/updates main contrib non-free

After this run a update again

apt-get update

apt-get upgrade

apt-get dist-upgrade

Okay now reboot (thumbs crossed)

root@gw:# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 8 (jessie)"
NAME="Debian GNU/Linux"
VERSION_ID="8"
VERSION="8 (jessie)"
ID=debian
HOME_URL="http://www.debian.org/"
SUPPORT_URL="http://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"
root@gw:#

You will probably encounter some problems. I had some problems with apache2, but after some searching, he is also up and running again.