I think it’s a different error (it’s looking for some repodata files that are no longer in the repository). The post was moved from 10/10/19 Cannot find a valid baseurl for repo: ce-base/7/x86_64 to a new topic.
You can try to solve the problem using these commands from the CentOS wiki:
yum clean all
rm -rf /var/cache/yum/* # warning: take extra care when running an rm command