Step 1 : rpm -e –nodeps redhat-release Step 2 : rpm -e –nodeps yum-rhn-plugin Step 3 : wget http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5 Step 4 : rpm –import RPM-GPG-KEY-CentOS-5 Step 5 : rpm -Uvh http://mirror.centos.org/centos/5/os/x86_64/CentOS/centos-release-notes-5.3-3.x86_64.rpm Step 6 : rpm -Uvh http://mirror.centos.org/centos/5/os/x86_64/CentOS/centos-release-5-3.el5.centos.1.x86_64.rpm Step 7 : wget http://mirror.centos.org/centos/5/os/x86_64/CentOS/yum-3.2.19-18.el5.centos.noarch.rpm Step 8 : yum clean all yum update