When you try to install something from the Yum command, you get this error:
Cannot find a valid baseurl for repo: core
This is because your download mirror list is old and the URLs are wrong / no longer exist.
To fix this, update your mirror list. I think these files are in:
- /etc/yum.repos.d/fedora.repo (core)
- /etc/yum.repos.d/fedora-updates.repo (updates)
I don’t know what the new mirrors are, or even if the new mirrors would hold the repositories for the old version you’re using.
Alternatively, uninstall Yum and rebuild all your applications from the source code.
Ideally, update to the latest version of Fedora.
There’s a good lot of information about this here, including steps to remediate.