12月后Centos 6 系统无法使用yum出现错误(文章底部看)
相信已经有一部分朋友今天连接到CentOS 6的服务器后执行yum后发现报错，那么发生了什么？
CentOS 6已经随着2020年11月的结束进入了EOL（Reaches End of Life），不过有一些老设备依然需要支持，CentOS官方也给这些还不想把CentOS 6扔进垃圾堆的用户保留了最后一个版本的镜像，只是这个镜像不会再有更新了
官方便在12月2日正式将CentOS 6相关的软件源移出了官方源，随之而来逐级镜像也会陆续将其删除。
不过有一些老设备依然需要维持在当前系统，CentOS官方也给这些还不想把CentOS 6扔进垃圾堆的用户保留了各个版本软件源的镜像，只是这个软件源不会再有更新了。
一键修复

sed -i "s|enabled=1|enabled=0|g" /etc/yum/pluginconf.d/fastestmirror.conf

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

curl -o /etc/yum.repos.d/CentOS-Base.repo https://www.xmpan.com/Centos-6-Vault-Aliyun.repo 

yum clean all

yum makecache

手动修复教程:
首先把fastestmirrors关了

#编辑

vi /etc/yum/pluginconf.d/fastestmirror.conf

#修改

enable=0
#或者执行以下命令
sed -i "s|enabled=1|enabled=0|g" /etc/yum/pluginconf.d/fastestmirror.conf

先把之前的repo挪到备份，然后下面两个二选一
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
替换为官方Vault源(海外服务器用)
curl -o /etc/yum.repos.d/CentOS-Base.repo https://www.xmpan.com/Centos-6-Vault-Aliyun.repo
或者替换为阿里云Vault镜像(国内服务器用)
curl -o /etc/yum.repos.d/CentOS-Base.repo https://www.xmpan.com/Centos-6-Vault-Aliyun.repo
下列是错误详情

[root@c8-20 ~]# yum makecache
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
 Eg. Invalid release/repo/arch combination/
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base

或者

[root@li496-237 ~]# yum -y install unzip zip
Loaded plugins: fastestmirror
Setting up Install Process
Determining fastest mirrors
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/repo/arch combination/
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/repo/arch combination/
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
Eg. Invalid release/repo/arch combination/
http://mirrors.linode.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
To address this issue please refer to the below knowledge base article 

https://access.redhat.com/articles/1320623

If above article doesn't help to resolve this issue please open a ticket with Red Hat Support.

Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again