Ubuntu版本升级时报Please install all available updates for your release before upgrading

在Ubuntu从16升级到18的时候，输入：

do-release-upgrade

出现如下提示：

Please install all available updates for your release before upgrading.

通过手动方式安装更新：

sudo apt update
sudo apt upgrade
sudo apt dist-upgrade
sudo do-release-upgrade

这样就可以安装成功。