Ubuntuアップデートの問題| 16.04;更新を完了できません
実行するたびに：
Sudo apt-get update
以下にこのメッセージが表示されます。
W: The repository 'cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release AMD64 (20160420.1) xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release AMD64 (20160420.1)/dists/xenial/main/binary-AMD64/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
E: Failed to fetch cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release AMD64 (20160420.1)/dists/xenial/main/binary-i386/Packages Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs
E: Failed to fetch ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu/dists/xenial/main/binary-AMD64/Packages 404 Not Found
E: Failed to fetch ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu/dists/xenial/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
使った
Sudo nano /etc/apt/sources.list
cdromを含む行をコメント化または削除します。例えば：
deb cdrom:[Ubuntu-Server 16.04 LTS Xenial Xerus - Release AMD64 (20160420.3)]/ xenial main restricted>
削除できました。 Sudo apt-get updateを実行すると、以下のエラーメッセージが表示されました。
W: The repository 'http://ppa.launchpad.net/ubuntu-on-Rails/ppa/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Failed to fetch http://ppa.launchpad.net/ubuntu-on-Rails/ppa/ubuntu/dists/xenial/main/binary-i386/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
誰もこれに光を当てることができますか？事前に感謝します。
使用しているPPAには、16.04で使用可能なパッケージがありません。これは、404エラーの意味です。
PPAを無効にするか、メンテナーに連絡してください。