我正在将更新应用到我的 AWS Ubuntu 14.04 服务器。我使用了以下命令：
sudo apt-get update
除一台服务器外，它适用于所有服务器。
我最后收到这个错误：
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/raring/main/binary-amd64/Packages 404 Not Found [IP: 91.189.91.23 80]
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/raring/universe/binary-amd64/Packages 404 Not Found [IP: 91.189.91.23 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
我尝试进行升级。我运行了以下命令：
# sudo apt-get upgrade
我看到了这个：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
lxc-docker
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
我应该怎么做才能应用更新？