Maak deze map als sudo leeg /etc/apt/sources.list.d met
sudo rm /etc/apt/sources.list.d/*
In deze map staan nu verouderde bronnen en PPA's die je systeem in de problemen hebben gebracht.
Vervolgens controleer je of je bronnen kloppen. In het bestand /etc/apt/sources.list moet voor 16.04 de onderstaande code staan. Misschien kan je het bestand beter helemaal leeg maken en de onderstaande tekst hierin plaatsen.
NB: de eerste regel is alleen commentaar bij installaties die ooit als 14.04 zijn begonnen. Die doet verder niets en is alleen ter informatie.
Het bestand kan je bewerken met
gksu mousepad /etc/apt/sources.list
# deb cdrom:[Ubuntu 14.04 LTS _Trusty Tahr_ - Release amd64 (20140414)]/ trusty main multiverse restricted universe
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://nl.archive.ubuntu.com/ubuntu/ xenial main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://nl.archive.ubuntu.com/ubuntu/ xenial-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://nl.archive.ubuntu.com/ubuntu/ xenial universe
deb http://nl.archive.ubuntu.com/ubuntu/ xenial-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://nl.archive.ubuntu.com/ubuntu/ xenial multiverse
deb http://nl.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://security.ubuntu.com/ubuntu xenial-security main restricted
deb http://security.ubuntu.com/ubuntu xenial-security universe
deb http://security.ubuntu.com/ubuntu xenial-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu xenial partner
# deb-src http://archive.canonical.com/ubuntu trusty partner
Hierna komen de opdrachten om op te ruimen, updates op te vragen en deze te installeren.
sudo apt remove software-properties-gtk
sudo apt clean
sudo apt update && sudo apt dist-upgrade
sudo apt install software-properties-gtk