How to backup before a release upgrade from Ubuntu 18.04.5 LTS server?

[Ralf Mardorf]

PS:
>*
 ^
 ^ The asterisk can only be used, if ther aren't any hidden items in
 the parent mount point directory. Subdirectories can contain hidden
 items. See "globbing".

>Linux provides sync software, but you don't need the advantages of a
>sync, so don't risk to suffer from doing mistakes when using sync
>software. Don't mess around with dd or similar commands.

FWIW "dd" isn't one of those sync commands, but it's still not a good
command to backup an install for several reasons.