Обновление Ubuntu 14.04 до 16.04 не работает

Эта команда sudo apt-get install update-manager-core не работает над обновлением Ubuntu 14.04 до 16.04.

Я получаю такой вывод:

Reading package lists... Done 
Building dependency tree
Reading state information... Done
update-manager-core is already the newest version.
The following packages were automatically installed and are no longer required:
 apache2.2-bin gdebi-core packagekit-backend-aptcc packagekit-tools python3-packagekit zlib1g-dev
Use 'apt-get autoremove' to remove them.
0 to upgrade, 0 to newly install, 0 to remove and 0 not to upgrade.
W: Duplicate sources.list entry http://ppa.launchpad.net/ondrej/php/ubuntu/trusty/main i386 Packages
(/var/lib/apt/lists/ppa.launchpad.net_ondrej_php_ubuntu_dists_trusty_main_binary-i386_Packages)
W: You may want to run apt-get update to correct these problems

Предыдущая команда была

sudo apt-get update && sudo apt-get dist-upgrade