1、确定/etc/yum.repos.d/下镜像源是否正确
(1)CentOS-Base.repo改成阿里云的vault源
(2)epel源如果不正确就删除
yum clean all && yum makecache
2、安装libicu-devel,执行命令yum install libicu-devel
3、卸载老版lnmp,安装lnmp1.8