Centos8于2021年年底停止了服务，大家再在使用yum源安装时候，出现下面错误“错误：Failed to download metadata for repo ‘AppStream’: Cannot prepare internal mirrorlist: No URLs in mirrorlist”
解决方法替换源
[root@c556b961f07f /]# cd /etc/yum.repos.d/
[root@c556b961f07f yum.repos.d]# sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-*
[root@c556b961f07f yum.repos.d]# sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-*