Error: Failed to download metadata for repo ‘appstream’ – CentOS 8

错误：

Error: Failed to download metadata for repo 'appstream': Cannot prepare internal mirrorlist: No URLs in mirrorlist

解决办法：

To migrate from CentOS 8 to CentOS Stream 8, run the following commands:

dnf --disablerepo '*' --enablerepo=extras swap centos-linux-repos centos-stream-repos

然后执行

dnf distro-sync