1. 备份源列表
sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup
2、修改更新源
打开源列表
sudo gedit /etc/apt/sources.list
用https://www.cnblogs.com/iamhenanese/p/5514111.html这个网址中的一些源替换
3、最后执行命令
sudo apt-get update
4、Ubuntu更新update源时出现AppStream cache update completed, but some metadata was ignored due to errors。
After that, upgrade to the version from xenial-backports by typing:
sudo apt install appstream/xenial-backports
Now your appstream package should be upgraded to version 0.10.1.
$ appstreamcli --version
AppStream CLI tool version: 0.10.1
Now force refreshing the cache data, you should no longer see any warning:
$ sudo appstreamcli refresh --force
AppStream cache update completed successfully.