After trying to upgrade from 17.04 to 18.0 this message appears:
E: The repository 'http://ppa.launchpad.net/jonathonf/vlc/ubuntu zesty Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. W: Target Sources (main/source/Sources) is configured multiple times in /etc/apt/sources.list.d/videolan-ubuntu-master-daily-zesty.list:2 and /etc/apt/sources.list.d/videolan-ubuntu-master-daily-zesty.list:3 E: The repository 'http://ppa.launchpad.net/videolan/stable-daily/ubuntu zesty Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://archive.ubuntu.com/ubuntu zesty Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://archive.ubuntu.com/ubuntu zesty-updates Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://archive.ubuntu.com/ubuntu zesty-backports Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://archive.ubuntu.com/ubuntu zesty-security Release' does not have a Release file. W: Updating from such a repository can't be done securely, and is therefore disabled by default. W: See apt-secure(8) manpage for repository creation and user configuration details. E: The repository 'http://archive.ubuntu.com/ubuntu zesty-proposed Release' does not have a Release file.
I have a netbook eMachines E350, Intel Atom processor, and 2GB RAM memory. Is it necessary to download the 18.04 ISO image?