ubuntu 16.04 升级 18.04 时报错”Invalid package information”

用 do-release-upgrade 命令准备将 ubuntu 16.04 服务器升级至 18.04，在升级过程中出现下面的错误：

After updating your package information, the essential package 'ubuntu-minimal' could not be located. This may be because you have no official mirrors listed in your software sources, or because of excessive load on the mirror you are using. See /etc/apt/sources.list for the current list of configured software sources. In the case of an overloaded mirror, you may want to try the upgrade again later.

请问如何解决？

回答

是 /etc/apt/sources.list 中的镜像源设置引起的，后来清空 sources.list 改为下面的阿里云镜像源解决了

deb http://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe