我一直在尝试使用以前适用于我的Debian Jessie构建的说明从Java 1.7升级到1.8。
这就是我在做什么：
sudo apt-get update
sudo apt-get upgrade
sudo apt install -t jessie-backports openjdk-8-jre-headless ca-certificates-java
sudo apt-get install openjdk-8-jre-headless
sudo update-alternatives --config java // select the jdk8 version
仅使用sudo apt-get update，我就会收到以下错误：
Err http://httpredir.debian.org jessie-updates/main Sources
404 Not Found [IP: 151.101.248.204 80]
Err http://httpredir.debian.org jessie-updates/contrib Sources
404 Not Found [IP: 151.101.248.204 80]
Err http://httpredir.debian.org jessie-updates/non-free Sources
404 Not Found [IP: 151.101.248.204 80]
Err http://httpredir.debian.org jessie-updates/main amd64 Packages
404 Not Found [IP: 151.101.248.204 80]
Err http://httpredir.debian.org jessie-updates/contrib amd64 Packages
404 Not Found [IP: 151.101.248.204 80]
Err http://httpredir.debian.org jessie-updates/non-free amd64 Packages
404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://cloudfront.debian.net/debian/dists/jessie-backports/main/source/Sources 404 Not Found [IP: 99.84.181.117 80]
W: Failed to fetch http://cloudfront.debian.net/debian/dists/jessie-backports/main/binary-amd64/Packages 404 Not Found [IP: 99.84.181.117 80]
W: Failed to fetch http://http.debian.net/debian/dists/jessie-backports/main/binary-amd64/Packages 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/main/source/Sources 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/contrib/source/Sources 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/non-free/source/Sources 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/main/binary-amd64/Packages 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/contrib/binary-amd64/Packages 404 Not Found [IP: 151.101.248.204 80]
W: Failed to fetch http://httpredir.debian.org/debian/dists/jessie-updates/non-free/binary-amd64/Packages 404 Not Found [IP: 151.101.248.204 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
我什至都不会进入下一个命令，即升级命令，因为该命令还会返回404。