Now that I have set up Navigatrix, that it works fine, I thought I would create a backup USB drive.

The "Make a copy for a friend" option had disappeared when I installed it, so following the advice on http://navigatrix.net/nxdoc/docs/getnx.html , I tried typing nxcopy in the terminal.

However, I get the following error, which is both disturbing and cryptic :

Does anybody have any advice ?
Thanks !

The easiest way to make another copy for a friend or yourself that I've used is just this: Boot up your system using the original install usb drive, and then once it's loaded completely, click on the icon "make a copy for a friend". It will then prompt you to insert another usb drive and hit "enter". Screen will turn green when finished. I just made two this way on Friday night, and they both work fine.

The 'Make A Copy For A Friend' is run by a script called nxcopy.

This copies the LiveCD image to another USB stick.

When a LiveCD image is installed it ceases being a LiveCD but becomes an installed system . The script (nxcopy) is not designed to copy installed systems, only LiveCDs.

In this context the error message is neither disturbing nor cryptic.

To make a copy/backup of an installed system the first thing you need to decide is if the copy/backup is a bootable 'copy' of the system, or just an archived 'copy'.

Thanks for the reply.
In my case I would like to make a bootable 'copy' of my install so as to be able to launch Nx from my USB drive in the event that the laptop partition fails. I like to have immediate backup solutions for when at sea...
Would you have any guidance as to how to do that ?

You may create a bootable usb stick with the startup disk creator (its in the preferences menu) Just select the navigatrix.iso within the startup disk creator and it will create a bootable medium for you which you may use in case your partition fails.