先看一下报错信息
已加载插件：fastestmirror
Loading mirror speeds from cached hostfile
http://vault.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
正在尝试其它镜像。
To address this issue please refer to the below wiki article
https://wiki.centos.org/yum-errors
If above article doesn't help to resolve this issue please use https://bugs.centos.org/.
One of the configured repositories failed (CentOS-7 - Base),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:
1. Contact the upstream for the repository and get them to fix the problem.
2. Reconfigure the baseurl/etc. for the repository, to point to a working
upstream. This is most often useful if you are using a newer
distribution release than is supported by the repository (and the
packages for the previous distribution release still work).
3. Run the command with the repository temporarily disabled
yum --disablerepo=base ...
4. Disable the repository permanently, so yum won't use it by default. Yum
will then just ignore the repository until you permanently enable it
again or use --enablerepo for temporary usage:
yum-config-manager --disable base
or
subscription-manager repos --disable=base
5. Configure the failing repository to be skipped, if it is unavailable.
Note that yum will try to contact the repo. when it runs most commands,
so will have to try and fail each time (and thus. yum will be be much
slower). If it is a very temporary problem though, this is often a nice
compromise:
yum-config-manager --save --setopt=base.skip_if_unavailable=true
failure: repodata/repomd.xml from base: [Errno 256] No more mirrors to try.
http://vault.centos.org/centos/7/os/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
问题点：提示我们找不到yum源
1.查看yum源配置是否正确
cd /etc/yum.repos.d/
ls -alh
2.修改配置文件 CentOS-Base.repo
vi CentOS-Base.repo #将配置文件里面的内容全部替换为下面内容
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the #mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
#baseurl=http://vault.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
#baseurl=http://vault.centos.org/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-$releasever - Extras
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#baseurl=http://vault.centos.org/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-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
#baseurl=http://vault.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
3.清楚缓冲生成新的缓冲
yum clean all
yum makecache
4.查看yum源是否配置正常
yum repolist
Centos8刚下载yum也是不能使用的
方法一：
直接执行如下命令：替换yum源
sudo sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-*
sudo sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*
方法二：
修改配置文件的方式：
备份：到/etc/yum.repos.d/备份CentOS-Linux-BaseOS.repo、CentOS-Linux-AppStream.repo文件 cp CentOS-Linux-BaseOS.repo CentOS-Linux-BaseOS.repo.bak(防止后续出现问题)
修改: (两个文件都需要执行)* 注释掉mirrorlist该行;
新增一行:baseurl=http://vault.centos.org/centos/$releasever/BaseOS/$basearch/os/
执行命令：yum clean all和yum makecache
查看是否成功：yum repolist
