Yum error Cannot retrieve metalink for repository

Yum provides installation, upgrades and removal of packages on Linux such as Centos. It is used to install other package repositories too. Over time, some of the certificates for installation would have changed and thats where you get this error when running Yum.

In this example, the error indicate Epel repository cannot be retrieved.

"Cannot retrieve metalink for repository: epel"

Some sysadmins have decided not to use that repo totally as they do not use that repo. E.g. when updating a package, they use

# yum --disablerepo="epel" update httpd

Solution

1. Clean yum cache
2. update the ca-certificate packages while disabling that repository with error.

Clean yum cache
# yum clean all

Update ca-certificate packages

In my Centos 6.3, it required to updated these related packages.