Couldn't execute /usr/bin/apt-key

最近尝试更新 vps 时遇到了不少如下错误:

错误:2 http://ftp.jp.debian.org/debian wheezy-updates InRelease                                                                                   
  Couldn't execute /usr/bin/apt-key to check /var/lib/apt/lists/partial/ftp.jp.debian.org_debian_dists_wheezy-updates_InRelease

它怎么了?好不容易活了这么多年,别挂啊……