yum安装报错（阿里云centos8.5.2111）

CentOS Linux 8 - AppStream    
Errors during downloading metadata for repository 'appstream':- Status code: 404 for http://mirror.centos.org/centos/8/AppStream/x86_64/os/repodata/repomd.xml (IP: **.**.**.254)
错误：为仓库 'appstream' 下载元数据失败 : Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors were tried

解决方案：删除repo文件 然后重新下载即可修复yum安装报错问题

1.进入/etc/yum.repos.d/目录

cd /etc/yum.repos.d/

2.备份原来的yum.repos.d文件

cd /etcmkdir backupcd backupmkdir yum.repos.d.ori

3.再次进入yum.repos.d目录中

cd /etc/yum.repos.d

执行备份

cp * /etc/backup/yum.repos.d.ori

4.删除yum.repos.d目录下的所有repo文件然后重新下载repo文件

cd /etc/yum.repos.d

rm -rf *

重新下载

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-vault-8.5.2111.repo

下载完成后 执行 

yum makecache

亲测有效：下图