Upgrade to version 1.6 from version 1.4
First perform all steps for upgrading from version 1.4 to 1.5, and then perform the steps of upgrading from version 1.5 to 1.6.
Upgrade to version 1.6 from version 1.3
First perform all steps for upgrading from version 1.3 to version 1.4, then for upgrading from version 1.4 to 1.5, and then finaly perform the steps of upgrading from version 1.5 to 1.6.