Updating Rasbian from Wheezy to Jessie and Stretch

Before … :-( $ sudo apt-get update Get:1 http://archive.raspberrypi.org wheezy Release.gpg \[488 B\] Ign http://mirrordirector.raspbian.org wheezy Release.gpg Get:2 http://archive.raspberrypi.org wheezy Release \[17.6 kB\] Ign http://mirrordirector.raspbian.org wheezy Release Err http://raspberrypi.collabora.com wheezy Release.gpg Something wicked happened resolving 'raspberrypi.collabora.com:http' (-5 - No address associated with hostname) Ign http://raspberrypi.collabora.com wheezy Release Get:3 http://archive.raspberrypi.org wheezy/main armhf Packages [144 kB] Err http://raspberrypi.collabora.com wheezy/rpi armhf Packages Something wicked happened resolving 'raspberrypi.collabora.com:http' (-5 - No address associated with hostname) Err http://raspberrypi.