yum报错：failure: repodata/repomd.xml from xxxxxx: [Errno 256] No more mirrors to try.解决办法

问题截图：

解决步骤：

1.删除老仓库

rm  -rf  /etc/yum.repos.d/*

2.卸载yum包

先查询已安装版本

rpm -qa yum

卸载

rpm -qa yum yum-3.4.3-150.el7.centos.noarch
卸载组件
rpm -qa | grep yum | xargs rpm -e --nodeps
在查询没有了
rpm -qa yum

3.下载最新的rpm包

下载地址：http://mirrors.163.com/centos/7/os/x86_64/Packages/
下载这三个：

wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-3.4.3-168.el7.centos.noarch.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpm
wget http://mirrors.163.com/centos/7/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.31-54.el7_8.noarch.rpm

4.重新安装yum

rpm -qa yum

5.导入证书

rpm --import http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-7

如果提示网络连接失败，可自行下载，然后从路径导入

6.设置阿里源

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

7.清除缓存，生成新的缓存

yum clean all
yum makecache

等待命令完成，在重写安装即可