maas / stable / ubuntu xenial存储库没有Release文件

当我在安装了MAAS的Ubunutu 16.04 LTS服务器上运行sudo apt update ,我收到以下错误消息:

 graeme@MAAS:~$ sudo apt update Hit:1 http://gb.archive.ubuntu.com/ubuntu xenial InRelease Hit:2 http://security.ubuntu.com/ubuntu xenial-security InRelease Ign:3 http://ppa.launchpad.net/maas/stable/ubuntu xenial InRelease Hit:4 http://gb.archive.ubuntu.com/ubuntu xenial-updates InRelease Err:5 http://ppa.launchpad.net/maas/stable/ubuntu xenial Release 404 Not Found Hit:6 http://gb.archive.ubuntu.com/ubuntu xenial-backports InRelease Reading package lists... Done E: The repository 'http://ppa.launchpad.net/maas/stable/ubuntu xenial Release' does not 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. 

这是我应该忽略或尝试修复的东西吗?

事实certificate,对于Xenial没有稳定的MAAS版本,这意味着我需要在ppa:maas/next存储库而不是ppa:maas/stable 。 这个问题是在逐步完成MAAS入门指南之后产生的,该指南要求我发布ppa:maas/stable存储库。 用它取出后

 sudo add-apt-repository --remove ppa:maas/stable 

更新没有任何错误。