Apt update stuck waiting for headers

Problem

I tried to update the apt cache on a machine that had not been updated in a long time:

$ sudo apt-get update

But that got stuck at one of the repositories Waiting for headers. No matter how many times I tried the command, it would get stuck at this.

Solution

The problem went away once I cleared the cache using these steps as explained here:

$ sudo apt-get clean
$ cd /var/lib/apt
$ sudo mv lists lists.old
$ sudo mkdir -p lists/partial
$ sudo apt-get clean
$ sudo apt-get update 

Tried with: Ubuntu 16.04