Centos 6 cannot run yum makecache

when I running yum makecache 

show me:
https://get.pkgs.cloud/updates/EL6/RPMS/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.

Try this url is not found . If I change it to EL7 will ok
How to use it in EL6
Please && Thanks