How to solve “Cannot retrieve metalink for repository: epel” Error in Centos 6

The server is CentOS 6.6 64bit. When I try ot run yum update the error shown as below:

Loaded plugins: fastestmirror, security
Determining fastest mirrors
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

The way to solve the problem is to edit

/etc/yum.repos.d/epel.repo

Modify https and replace them by http
Save it then run yum update.