Greg, according to the release notes "Known Issues" section ( https://wiki.centos.org/Manuals/ReleaseNotes/CentOS7?action=show&redirect=Manuals%2FReleaseNotes%2FCentOS7.1708#head-281c090cc4fbc6bb5c7d4cd82a266fce807eee7c ) you need to run "yum downgrade libgpod" first. I have updated a dozen or so machines to 7.4.1708, and several needed this.