I went to update my Fedora Core 5 machine today, and received the following error:
[root ~] yum check-update
Loading "installonlyn" plugin
Setting up repositories
core [1/3]
Cannot find a valid baseurl for repo: core
Error: Cannot find a valid baseurl for repo: core
I tried running yum clean all but it didn’t help. After looking around I found that all of my repo files in /etc/yum.repos.d/ had their baseurl values commented out. Don’t ask me how that happened, I have no idea. Simply un-commenting all the baseurl values in all my repo files fixed the problem, and yum is once again running as expected. So if you run into this problem, make sure everything is set up right in /etc/yum.repos.d/*.repo