CentOS 7 操作系统在2024年6月30日后将停止官方维护，并且官方提供的YUM源将不再可用。

修改：nano /etc/yum.repos.d/CentOS-Base.repo

# CentOS-Base.repo   
[base]  
name=CentOS-$releasever - Base  
baseurl=http://mirrors.aliyun.com/centos/$releasever/os/$basearch/  
        http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/  
gpgcheck=1  
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7  
  
#released updates   
[updates]  
name=CentOS-$releasever - Updates  
baseurl=http://mirrors.aliyun.com/centos/$releasever/updates/$basearch/  
        http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/  
gpgcheck=1  
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7  
  
#additional packages that may be useful  
[extras]  
name=CentOS-$releasever - Extras  
baseurl=http://mirrors.aliyun.com/centos/$releasever/extras/$basearch/  
        http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/  
gpgcheck=1  
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7  
  
#additional packages that extend functionality of existing packages  
[centosplus]  
name=CentOS-$releasever - Plus  
baseurl=http://mirrors.aliyun.com/centos/$releasever/centosplus/$basearch/  
        http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$basearch/  
gpgcheck=1  
enabled=0  
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7  
  
#contrib - packages by Centos Users  
[contrib]  
name=CentOS-$releasever - Contrib  
baseurl=http://mirrors.aliyun.com/centos/$releasever/contrib/$basearch/  
        http://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/contrib/$basearch/  
gpgcheck=1  
enabled=0  
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7  
  
#
failovermethod=roundrobin

yum clean all
yum makecache
yum update

恢复正常：