Why might a "yum upgrade" appear to work but not actually apply anything?

I have a server running CentOS (with Fasthosts UK).

Running a "yum upgrade" lists - and processes - a LOT of packages that it has upgrades for. Everything is downloaded and installed.

The problem is that if I do a subsequent "yum upgrade", it list all the same upgrades again! As if it was only running as a simulation and didn't really apply any upgrades.

This effectively means that I can't upgrade any of the software packages on my server ("yum upgrade specificpackage" also has the same problem) and so I wondered if anybody has any kind of experience or advice about this?

Is this a CentOS issue or a Fasthosts issue?

PS. FWIW there is also Plesk intalled on this server.

From serverfault Dougal

• I haven't seen this specifically, but the first thing I would try is yum clean all to clean up package data, caches and the rpm database. Then see if you get the same results after another update.

  From Alex

• Based on that log snippet, it looks like you may have some repository priority conflicts. In my experience, the various repositories for CentOS are not well-coordinated. RPMForge doesn't always play nicely with EPEL, for example, and you get version number races.

  To get more information, you could make yum run in verbose mode with the -d (debug) and -e (error level) switches. NUM should be between 1 and 10.

  You might also try using --skip-broken, which should only hold back the package that's causing problems.

  Dougal : Some v. useful info - thanks, I'll investigate. I have indeed added the RPMForge repo.

  Dougal : --skip-broken sounds great and I was actually imagining using something like that - will try - thanks

  troyengel : upboat - the problem is that yum is bailing out on you due to an error, so the right thing is actually happening. --skip-broken is your friend if you don't want to debug further, eventually it will get fixed upstream and work later (usually :) ).

  Dougal : yum upgrade --disablerepo=rpmforge seems to be churning away now!
  From Tristan

• In your comments you say there is a "transaction check error". This is likely the problem. You should paste that here, although depending on what the problem was, it may have solved itself by now.

  As other posters pointed out, some of the third party repos. are not very well managed. At most I would recommend: RHEL, EPEL, rpmfusion* and iuscommunity.

  From James Antill