Upgrading from C15 to C16

[swarfendor437]

See the post by Artyom Zorin here:

Upgrade from zorin 15 to 16 (ultimate)

We are planning to introduce a direct upgrade path from Zorin OS 15 to 16 without the need to do a clean re-installation. However, please note that we will make this option available a number of months after the initial release of Zorin OS 16, after a thorough testing period has been completed. As a result, if you wish to upgrade from Zorin OS 15.3 as soon as Zorin OS 16 is initially released, you will need to do a clean install.