As I presented in a previous post the 64bit version of Centos 4.x has some problems with the latest updated kernels that result in up2date failing from functioning with the following error:

up2date -l

Fetching Obsoletes list for channel: centos4-Base...

Fetching Obsoletes list for channel: centos4-Updates...

Fetching Obsoletes list for channel: centos4-extras...

Fetching Obsoletes list for channel: centos4-addons...
An error has occurred:
exceptions.KeyError
See /var/log/up2date for more information

Again in logs we can see that it fails to find the proper architecture for the kernel-smp package:

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up2date Could not find an approriate arch for package [['kernel-smp', '2.6.9', '34.0.1.EL', '', 'x86_64', '1000', 'centos4-Updates', 'RPMS/kernel-smp-2.6.9-34.0.1.EL.x86_64.rpm']], skipping

And as in my previous post a quick solution to fix this problem, is to install manually the updated package to fix this problem:

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rpm -ivh http://mirror.centos.org/centos/4/updates/x86_64/RPMS/\
kernel-smp-2.6.9-34.0.1.EL.x86_64.rpm

And, up2date will start working again :-).