I would like to add full disk encryption to Ubuntu 18.04. I am aware it is not really possible without reinstalling the OS. I'm wondering if I can backup certain directories with Deja Dup then reinstall an encrypted OS then restore the files from Deja Dup and have all of my apps/settings/files all be the same.
Is this possible at all? If so which directories should I back up with Deja Dup?
I have tried to back up the "/" directory (full file system) and that always seems to error.