The TurnKey v14.0 & v14.1 ownCloud appliances use the Debian package, rather than installing from upstream. For these versions, that means ownCloud v7.0.4.

The v14.2 ownCloud appliance shipped with ownCloud v10.0.2 installed directly from ownCloud themselves using the downloaded tarball.

If you would like to migrate from the official Debian package to the upstream Debian package, then there is a (quite dated and untested) doc for that. If you do attempt to follow that doc, please give feedback on how you went. We would especially welcome reports of success/failure and any other additional info, etc! Even though that is no longer this is no longer the recommended method, it should still work ok.

The recommended install method is now downloading the upstream ownCloud tarball directly. However, there is not currently a documented way to do that, so will likely be a case of trial and error. Unfortunately, ownCloud do not appear to provide instructions for updating from v7.x (or even v8.x) to currently supported versions, however, they do provide older versions as well as upgrade instructions here and here.

If you hit issues and would like a hand, please post in our forums and we'll do our best to help out.