Yum Repo Issues

My CentOS-Base.repo has the following mirrors:

[base]
name=CentOS-$releasever - Base
baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
enabled=1

#released updates
[updates]
name=CentOS Server updates
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
baseurl=http://custom-url/centOS-updates/
enabled=1

When I say yum install yum-utils, it fails with the error saying

http://custom-url/centOS-updates/Packages/yum-utils-1.1.31-46.el7_5.noarch.rpm: [Errno 14] HTTP Error 500 - Internal Server Error Trying other mirror. Error downloading packages: yum-utils-1.1.31-46.el7_5.noarch: [Errno 256] No more mirrors to try.

I have two questions here:

• Why is it looking at the `updates` repo instead of base. `yum info yum-utils` has the repo field set to `updates`. When I disable the `updates` repo in the repo file and do a `yum info yum-utils` it shows the repo field as `base` correctly. What decides the repo to look at given a package?
• Why is 'Package' appended to the baseUrl when it tries to find yum-utils in the updates repo? This is causing a `500 Internal Server Error` as the path with Packages appended to it is invalid

Answer

A first-aid to internal server error from Yum is most likely a corrupt repodata on the remote server and/or mismatch cache between the client and server.

To wipe-clean the cache, use

$ yum --enablerepo=* clean all

or just this, if all the repos are enabled by default:

$ yum clean all

This does all the clean up available in yum. Here are what they do:

 CLEAN OPTIONS
   The following are the ways which you can invoke yum in clean mode. Note that "all files" in the commands below means "all files in currently  enabled  reposito‐
   ries".  If you want to also clean any (temporarily) disabled repositories you need to use --enablerepo='*' option.

   yum clean expire-cache
          Eliminate  the local data saying when the metadata and mirrorlists were downloaded for each repo. This means yum will revalidate the cache for each repo.
          next time it is used. However if the cache is still valid, nothing significant was deleted.

   yum clean packages
          Eliminate any cached packages from the system.  Note that packages are not automatically deleted after they are downloaded.

   yum clean headers
          Eliminate all of the header files, which old versions of yum used for dependency resolution.

   yum clean metadata
          Eliminate all of the files which yum uses to determine the remote availability of packages. Using this option will force yum to download all the metadata
          the next time it is run.

   yum clean dbcache
          Eliminate the sqlite cache used for faster access to metadata.  Using this option will force yum to download the sqlite metadata the next time it is run,
          or recreate the sqlite metadata if using an older repo.

   yum clean rpmdb
          Eliminate any cached data from the local rpmdb.

   yum clean plugins
          Tell any enabled plugins to eliminate their cached data.

   yum clean all
          Does all of the above.