宝塔官方解决办法(我测试没能解决，但是我执行了一遍)

1、备份原来的yum源，

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

centos7：

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

centos8：

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-8.repo

更换后执行：

yum  clean  all

清除原来的yum源缓存
然后执行

yum makecache

生成新的yum源缓存

阿里云方法

配置方法

1. 备份

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup

2. 下载新的 CentOS-Base.repo 到 /etc/yum.repos.d/

CentOS 6

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-6.repo

CentOS 7

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

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo

CentOS 8

wget -O /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-8.repo

或者

curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-8.repo

3. 运行 'yum makecache '生成缓存

4. 其他

非阿里云ECS用户会出现 Couldn't resolve host 'mirrors.cloud.aliyuncs.com' 信息，不影响使用。用户也可自行修改相关配置: eg:

sed -i -e '/mirrors.cloud.aliyuncs.com/d' -e '/mirrors.aliyuncs.com/d' /etc/yum.repos.d/CentOS-Base.repo

原文链接：https://bbs.kuruiit.com/d/56-yum