已经有近六天了，软件更新程序没有显示 Ubuntu 16.04 的任何更新。
我努力了此解决方案，但不起作用。软件更新程序显示此信息：
运行后终端的输出sudo apt-get update为：
hirak@ubuntu:~$ sudo apt-get update
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:2 http://dl.google.com/linux/chrome/deb stable Release
Hit:3 http://in.archive.ubuntu.com/ubuntu xenial InRelease
Ign:5 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial InRelease
Get:6 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Get:7 http://in.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Hit:8 http://ppa.launchpad.net/ubuntu-wine/ppa/ubuntu xenial InRelease
Hit:9 http://ppa.launchpad.net/webupd8team/java/ubuntu xenial InRelease
Get:10 http://in.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Ign:11 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial Release
Ign:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Ign:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Ign:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Ign:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Ign:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Err:12 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 Packages
404 Not Found
Ign:13 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main i386 Packages
Ign:14 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main all Packages
Ign:15 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en_IN
Ign:16 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main Translation-en
Ign:17 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main amd64 DEP-11 Metadata
Ign:18 http://ppa.launchpad.net/nae-team/ppa/ubuntu xenial/main DEP-11 64x64 Icons
Fetched 306 kB in 16s (18.4 kB/s)
Reading package lists... Done
W: The repository 'http://ppa.launchpad.net/nae-team/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/nae-team/ppa/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
运行后终端的输出sudo apt-get dist-upgrade为：
hirak@ubuntu:~$ sudo apt-get dist-upgrade
[sudo] password for hirak:
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
hirak@ubuntu:~$
这是什么问题？如何解决？请帮帮我...提前谢谢...
答案1
有两件事 - 第一：launchpad.net/nae-team存储库没有适用于 Ubuntu 16.04 的软件包。
这就是您收到错误消息的原因 - 要删除 PPA，请执行以下命令：
sudo apt install ppa-purge
sudo ppa-purge nae-team/ppa
sudo apt update
第二：最近几天没有发布针对 Ubuntu 16.04 的更新 ->Ubuntu 更新
这就是您这么久没有收到 Ubuntu 16.04 LTS 更新的简单原因。
上次更新时间是lxd（2.7-0ubuntu2~ubuntu16.04.1）来自backports2016-12-28 的 repo。
此日期之后发布的 Ubuntu 16.04 的第一个更新是 2017-01-03 18.00 UTC。
更新您的评论，您仍然收到错误消息- 按如下方式进行。
/etc/apt/sources.list.d运行以下命令检查文件夹中的 PPA 条目：sudo ls -l /etc/apt/sources.list.d然后删除每个nae-team相关.list文件。
运行以下命令删除每个文件：sudo rm /etc/apt/sources.list.d/<name-of-the-file>.list
还可以通过运行以下命令检查/etc/apt/sources.list文件：sudo nano /etc/apt/sources.list
删除 PPA 的所有现有条目，然后按Ctrl+X关闭文件并Y保存这些更改。之后sudo apt update再次执行，现在它应该可以按预期工作。