sudo apt get update 관련 문제점 : 저장소 cdrom…에 릴리스 파일이 없습니다.

sudo apt-get update우분투를 업데이트 할 때 마다이 문제가 발생합니다.

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.

어떻게 고칠 수 있습니까?
우분투 16.04 LTS를 사용합니다

터미널에서이 문제를 해결하려면이 CD-ROM 저장소 소스를 직접 제거하거나 주석 처리해야합니다. /etc/apt/sources.list

 sudo nano /etc/apt/sources.list

cdrom 을 포함하는 행을 주석 처리하거나 제거하십시오 . 예 :

deb cdrom:[Ubuntu-Server 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.3)]/ xenial main restricted

이 시도 :
오픈 소프트웨어 및 업데이트 하고있는 우분투 소프트웨어 의 선택을 취소 탭 우분투 16.04 LTS '주객 관계의 Xerus'와 CDROM 섹션에서 CD-ROM / DVD에서 설치 가능 .