Ubuntu 常见错误--Package has no installation candidate解决方法

今天在安装软件的时候出现了Package has no installation candidate的问题，错误信息以及解决办法如下：

apt-get install packagename
Reading package lists… Done
Building dependency tree… Done
Package aptitude is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package packagename has no installation candidate

Terminal command
$ apt-get update
$ apt-get upgrade
$ apt-get install packagename