How Canonical makes money from Ubuntu
There are three active LTS releases of Ubuntu: 12.04, 14.04 and 16.04. The support for 12.04 is ending this year on April 28, 2017. While Canonical is encouraging users to upgrade to 14.04 or 16.04 LTS, there are still a lot of companies using 12.04.
Customers running critical services on their servers and cloud really don’t like frequent upgrades. They tweak, tune and customize different components of their infrastructure and when you bring in too many changes at the same time with a major release upgrade, something is going to break.