I'm not sure what your asking here. I am a Fedora user and have encountered problems while doing updates. Usually though, it's only when trying out the betas of unreleased versions.
When updates fail using yum, there will be a message that asks you to try --skip-broken to allow the update to go through. This is most likely due to a missing dependency, and that problem is usually resolved by waiting a day or two.
BTW - I don't use the -y parameter, it's dangerous as it answers yes to all questions that yum may come up with during the action being performed.
#yum --skip-broken update
usually solves most problems with update.