I was trying to use sudo apt-get install build-essentials to install the g++ compiler on my Ubuntu Linux box. But it gave me the following message:

Reading package lists... Done

Building dependency tree
Reading state information... Done

E: Unable to locate package build-essentials

How do I fix this problem?

Drop the 's' off of the package name.

You want sudo apt-get install build-essential

You may also need to run sudo apt-get update to make sure that your package index is up to date.

For anyone wondering why this package may be needed as part of another install, it contains the essential tools for building most other packages from source (C/C++ compiler, libc, and make).