Number 1 i have only discovered NethServer.
Number 2 V8 is still being developed
Number 3 i only will install a new OPSYS if it is at least at V. 8.2
and it can be converted from V7 to V 8 …
If there are only a few users, it is easier to create them on the user interface after installing an account provider module on NethServer: either samba AD/DC (nethserver-dc) or openLDAP (nethserver-directory).
If many users, then you can create them by importing them after ONE of those account provider modules is installed.
For a remote AD account provider, the users must be managed from the main AD server (not from NethServer).
First import the users, then import the groups (optionally with users assigned to each one).
Do not know… maybe it didn’t recognize the file formatting.
The related log excerpts from /var/log/messages might tell us more about why it didn’t work.
EDIT: run the command as root.
I believe the example on the manual for importing groups has a typo (it says import_users instead of import_groups).