> #Ubuntu 20.04 LTS is due to be released on April 23, 2020, succeeding Ubuntu 19.10 as the latest stable release.

https://www.omgubuntu.co.uk/2019/10/ubuntu-20-04-release-features

现在的 18.04 是从 16.04 升级上来的，过几天发布的 20.04 还是干净安装吧，正好系统已经积攒了很多冗杂的东西。