at the moment, if I use this command on 19.04:
I get this answer:
E: The repository 'http://ppa.launchpad.net/univention-dev/ppa/ubuntu disco Release' does not have a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details.
If installed on 18.10 and then upgraded, the client is still in the domain, but it takes much longer to do so.
I need this quite urgently for a customer who wants to join more than 200 clients.
Can this be fixed on short notice?