CentOS yum updateエラー

yumコマンドで操作してもエラーが出てうまく動かない様子だったので調査

# yum check-update
Loaded plugins: fastestmirror, security
Determining fastest mirrors
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
 Eg. 6.5 is not a valid and current release or hasnt been released yet/
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6.5/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base

# cat /etc/redhat-release
CentOS release 6.5 (Final)

この中で、

Eg. 6.5 is not a valid and current release or hasnt been released yet

が気になって調べてみた結果、

# rm /etc/yum/vars/releasever

でいけた。ちなみに何が書いていたかというと、

# cat /etc/yum/vars/releasever
6.5

だった