# apt update
Ign:2 http://httpredir.debian.org/debian stretch InRelease                                                              
Ign:3 http://security.debian.org stretch/updates InRelease                                                              
Ign:4 http://httpredir.debian.org/debian stretch-updates InRelease                 
Err:5 http://security.debian.org stretch/updates Release
  404  Not Found [IP: 2a04:4e42:8d::644 80]
Hit:1 http://fi.mirror.armbian.de/apt stretch InRelease
Get:6 https://deb.nodesource.com/node_9.x stretch InRelease [4,623 B]
Ign:7 http://httpredir.debian.org/debian stretch-backports InRelease                 
Err:8 http://httpredir.debian.org/debian stretch Release
  404  Not Found [IP: 2a04:4e42:8d::644 80]
Err:9 http://httpredir.debian.org/debian stretch-updates Release
  404  Not Found [IP: 2a04:4e42:8d::644 80]
Err:10 http://httpredir.debian.org/debian stretch-backports Release
  404  Not Found [IP: 2a04:4e42:8d::644 80]
Reading package lists... Done
E: The repository 'http://security.debian.org stretch/updates Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://httpredir.debian.org/debian stretch Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://httpredir.debian.org/debian stretch-updates Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://httpredir.debian.org/debian stretch-backports Release' does no longer have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.