Traceback (most recent call last) : File "/usr/bin/yum", line 28, in ? import yummain ImportError: No module named yummain
I tried doing yum clean all, but the error came up even for this command. To solve the issue, I've used rpm and re-install yum-3.2.22-20.el5.centos.noarch.rpm from the CentOS 5.4 DVD again and the problem ceased.
rpm -Uvh yum-3.2.22-20.el5.centos.noarch.rpm
On another note, there were some solution on Google suggesting to install yum-complete-transaction. Now that was quite painful. I did a yum install yum-complete-transaction. But it actually meant a
yum install yum-utils