这样做apt-get update会出现以下错误：
Ign http://security.debian.org squeeze/updates Release.gpg
Ign http://security.debian.org/ squeeze/updates/contrib Translation-en
Ign http://security.debian.org/ squeeze/updates/contrib Translation-en_GB
Ign http://security.debian.org/ squeeze/updates/main Translation-en
Ign http://security.debian.org/ squeeze/updates/main Translation-en_GB
Ign http://security.debian.org/ squeeze/updates/non-free Translation-en
Ign http://security.debian.org/ squeeze/updates/non-free Translation-en_GB
Ign http://security.debian.org squeeze/updates Release
Ign http://security.debian.org squeeze/updates/main Sources
Ign http://security.debian.org squeeze/updates/contrib Sources
Ign http://security.debian.org squeeze/updates/non-free Sources
Ign http://security.debian.org squeeze/updates/main amd64 Packages
Ign http://security.debian.org squeeze/updates/contrib amd64 Packages
Ign http://security.debian.org squeeze/updates/non-free amd64 Packages
Err http://security.debian.org squeeze/updates/main Sources
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/contrib Sources
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/non-free Sources
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/main amd64 Packages
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/contrib amd64 Packages
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/non-free amd64 Packages
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
25% [Connecting to ftp.de.debian.org (141.76.2.4)]^C
root@ks3309152:/# nano /etc/apt/sources.list
root@ks3309152:/# nano /etc/apt/sources.list.backup
root@ks3309152:/# nano /etc/apt/sources.list
root@ks3309152:/# apt-get update
Ign http://debian.mirrors.ovh.net squeeze Release.gpg
Ign http://debian.mirrors.ovh.net/debian/ squeeze/main Translation-en
Ign http://security.debian.org squeeze/updates Release.gpg
Ign http://debian.mirrors.ovh.net/debian/ squeeze/main Translation-en_GB
Ign http://security.debian.org/ squeeze/updates/main Translation-en
Ign http://security.debian.org/ squeeze/updates/main Translation-en_GB
Ign http://debian.mirrors.ovh.net squeeze Release
Ign http://debian.mirrors.ovh.net squeeze/main Sources
Ign http://security.debian.org squeeze/updates Release
Ign http://debian.mirrors.ovh.net squeeze/main amd64 Packages
Ign http://security.debian.org squeeze/updates/main Sources
Ign http://security.debian.org squeeze/updates/main amd64 Packages
Err http://security.debian.org squeeze/updates/main Sources
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://security.debian.org squeeze/updates/main amd64 Packages
404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
Err http://debian.mirrors.ovh.net squeeze/main Sources
404 Not Found [IP: 2001:41d0:202:100:213:32:5:7 80]
Err http://debian.mirrors.ovh.net squeeze/main amd64 Packages
404 Not Found [IP: 2001:41d0:202:100:213:32:5:7 80]
W: Failed to fetch http://debian.mirrors.ovh.net/debian/dists/squeeze/main/source/Sources.gz 404 Not Found [IP: 2001:41d0:202:100:213:32:5:7 80]
W: Failed to fetch http://debian.mirrors.ovh.net/debian/dists/squeeze/main/binary-amd64/Packages.gz 404 Not Found [IP: 2001:41d0:202:100:213:32:5:7 80]
W: Failed to fetch http://security.debian.org/dists/squeeze/updates/main/source/Sources.gz 404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
W: Failed to fetch http://security.debian.org/dists/squeeze/updates/main/binary-amd64/Packages.gz 404 Not Found [IP: 2001:a78:5:1:216:35ff:fe7f:6ceb 80]
E: Some index files failed to download, they have been ignored, or old ones used instead.
我意识到我距离当前版本还有 3 个主要版本，根据我收到的错误，我需要做什么才能正确升级到 Debian Stretch？
答案1
我会直接跳到 wheezy，但如果您想事先运行 squeeze 的更新，您可以将您的sources.list指向改为archive.debian.org。
deb http://archive.debian.org/debian-security squeeze/updates main
deb http://archive.debian.org/debian squeeze main
deb http://archive.debian.org/debian squeeze-lts main
deb http://archive.debian.org/debian squeeze-proposed-updates main
答案2
我认为通过这种方式你就可以升级。
首先将 Debian Squeeze 升级到 Wheezy。
然后将 Debian Wheezy 升级到 Jessie。
如何安全地将 Debian Wheezy 升级到 Jessie
最后将 Debian Jessie 升级到 9 Stretch。