Errors during downloading metadata for repository 'AppStream'

问题报错如下：

CentOS-8 - AppStream                                                                                                                                   0.0  B/s |   0  B     00:00    
Errors during downloading metadata for repository 'AppStream'

到 /etc/yum.repos.d/目录下编辑

# CentOS-AppStream.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#

[AppStream]
name=CentOS-$releasever - AppStream
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=AppStream&infra=$infra
baseurl=http://mirrors.aliyun.com/centos/8-stream/AppStream/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#

[BaseOS]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=BaseOS&infra=$infra
baseurl=http://mirrors.cloud.tencent.com/centos/$releasever/BaseOS/$basearch/os/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial

然后

yum clean all

yum makecache 

重建元数据缓存，