CentOS 8 Error: Failed to download metadata for repo ‘appstream‘: Cannot prepare internal mirrorlist

在控制台输入以下两行代码

sed -i 's/mirrorlist/#mirrorlist/g' /etc/yum.repos.d/CentOS-Linux-*
sed -i 's|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g' /etc/yum.repos.d/CentOS-Linux-*