https://ftp.riken.jp/Linux/centos/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found Trying other mirror. To address this issue please refer to the below knowledge base article
https://access.redhat.com/articles/1320623
If above article doesn't help to resolve this issue please create a bug on https://bugs.centos.org/
One of the configured repositories failed (CentOS-7 - Addons), and yum doesn't have enough cached data to continue. At this point the only safe thing yum can do is fail. There are a few ways to work "fix" this:
（略）
failure: repodata/repomd.xml from addons: [Errno 256] No more mirrors to try. https://ftp.riken.jp/Linux/centos/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
