CentOS Update [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found

http://mirrors.aliyun.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.
http://mirrors.aliyuncs.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 7 - “couldn’t connect to host”
Trying other mirror.
http://mirrors.cloud.aliyuncs.com/centos/6/os/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 6 - “Couldn’t resolve host ‘mirrors.cloud.aliyuncs.com’”
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
vi CentOS-Base.repo
:%s/$releasever/7/g #将文件中$releasever全部改成7
yum clean all && yum makecache # 清除和缓存

• $releasever 是获取你centos的版本号的，例如我的centos的版本号为6.7，获取到的为6，但是已经找不到了，所以直接全局改成7即可