yum 报错YumRepo Error: All mirror URLs are not using ftp, http[s] or file. Error: Cannot find a valid_yumerror all

yum 报错YumRepo Error: All mirror URLs are not using ftp, http[s] or file.

Error: Cannot find a valid baseurl for repo: base

<1> 

1、备份你的原镜像文件，以免出错后可以恢复。 命令如下： 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/；请选择相应的版本即可！ 命令如下：

CentOS 5

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo

CentOS 6

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

CentOS 7

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

3、运行yum makecache生成缓缓存； 命令： yum clean all yum makecache

<2> 发现还是报错

http://mirrors.aliyuncs.com/centos/5/os/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404: Not Found 
Trying other mirror. 
http://mirrors.aliyun.com/centos/5/os/i386/repodata/repomd.xml: [Errno 14] HTTP Error 404: Not Found 
Trying other mirror. 
Error: Cannot retrieve repository metadata (repomd.xml) for repository: base. Please verify its path and try again
 

cd  /etc/yum.repos.d
sed -i 's/mirrors.aliyun.com\/centos\/$releasever/vault.centos.org\/5.11/g' CentOS-Base.repo
sed -i 's/mirrors.aliyuncs.com\/centos\/$releasever/vault.centos.org\/5.11/g' CentOS-Base.repo
 

1. yum clean all

2. yum makecache