On Mon, 18 Mar 2019 07:53:56 +0100 c5244714@gmail.com wrote:

Hello.I'm using NAV version 4.9.2 and need your detail instruction about how to actually perform the upgrade.

Hi,

this depends entirely on how you installed NAV in the first place. If you, as most people do, installed the Debian package, then the procedure is a standard package update using apt-get (i.e. `apt-get update` followed by either `apt-get upgrade` or `apt-get install nav`).