I had the same problem. I am using CentOS 5.2 behind a proxy. The above advice fixed the issue.

Using "yum -y remove yum-fastestmirror" also removed yum with it (dependency!) which wasn't exactly good.

So far i tried
yum clean all
but no go.
yum clean metadata
but no go.
yum -y remove fastest-mirror
but no go

I have found that sometimes the upstream mirror has a corrupt metadata file, possibly caused by running buildrepo while files were still being updated or something like that. The only solution then seems to be to wait 4-24 hours and try again.

Another solution, and one I've since done, is to build your own repository. You just need a web server with ~5 GB free space per version+architecture combination you use, an upstream repo to mirror from (I asked and got permission from GA Tech) and a couple of shell scripts (there are links on centos.org you can read more about this). Then you just modify the /etc/yum.repos.d/CentOS-Base.repo file on each of your servers to point to your repo instead of using the default mirror list for the Base, Updates, Extras and Addons repos, and you're in charge of your own fate.

Updates and kickstarts go a LOT faster when you have your own repository. And if your bosses agree (mine didn't), you can give back to the community by making your repo available over the Internet to other users.

Made the bonehead mistake and tried to uninstall yum-fastestmirror and it also removed yum-updatesd, yum-fastestmirror, yum, and pirut.

For anyone else who made this mistake here is the fix.

cat /etc/redhat-release (Will tell you what version your running)

Web to http://vault.centos.org/5.3/os/i386/CentOS/ (change the centos ver #)

Look for yum & yum-fastestmirror and copy and paste the link to wget

==Download rpm files to local hdd==
wget http://vault.centos.org/5.3/os/i386/...tos.noarch.rpm
wget http://vault.centos.org/5.3/os/i386/...tos.noarch.rpm

==Install Yum==
rpm -ivh yum-3.2.19-18.el5.centos.noarch.rpm yum-fastestmirror-1.1.16-13.el5.centos.noarch.rpm

==Disable Fastest Mirror==
/etc/yum/pluginconf.d/fastestmirror.conf
enabled=0 <--Disabled Fastest Mirror

==Test yum==
yum clean all
yum clean metadata
yum update

I know this thread is a bit old, but I just ran across it as I was searching for an answer and wanted to add to the collective knowledge of what worked for me.

It appears that this issue is likely to be caused by http caching on the server (repo) side. The reason that "yum clean all" won't fix the problem immediately is because yum will just download the cached out of date metadata file again. Until the repo http server's cache times out and caches the new metadata file, you'll keep getting the old metadata file and yum will keep complaining.

You can instruct yum not to use http caching, however. To do so globally, just add this option under the [main] section in /etc/yum.conf:

Now run yum clean all and yum check-update and you should be good to go!

I haven't tested it, but I would assume that you could also specify this option at a repo level instead of globally if you prefer.

All credit goes to this excellent article:
http://plone.lucidsolutions.co.nz/li...match-checksum

1 members found this post helpful.

Thanks Gato Azul. You are a savior.

I tried all the previous options, including
-> vi /etc/yum/pluginconf.d/fastestmirror.conf & set enabled=0
-> yum clean all
-> rpm --rebuilddb
even the one with adverse side effects
-> yum -y remove yum-fastestmirror
The above command removed yum. I used the CD I used to install the OS, and the following commands to get it back
-> cd /media/CDROM/CentOS
-> rpm -Uvh yum-3.2.19*.rpm yum-fastestmirror-*.rpm

Finally, what worked was as you mention in your post.
-> vi /etc/yum.conf (add the line http_caching=none under section [main])
-> yum clean all

I stumbled upon this thread while searching for "yum metadata file does not match checksum" online.
I would like to add some useful recon to this thread:

Root cause of problem:
I had a Scientific Linux 5.3 test server that I backed up to a local tar file, upgraded to 5.7 and then restored the backup to take it back down to 5.3 (testing rollback prior to patching production servers).
After rolling back to 5.3, I then reinitiated an upgrade and ran into this problem. yum returned the "metadata file does not match checksum" error.

Solution:
Following that, I was able to proceed with a full upgrade to 5.7 as normal.

Thank you, LinuxQuestions.org and its community, yet again, for hosting good information and showing up with high relevance in search results.