I get this: Code: root@web01:/# /usr/local/ispconfig/server/server.sh W: GPG error: [URL]http://extras.ubuntu.com[/URL] trusty Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A 3E5C1192 /usr/bin/fail2ban-client /sbin/iptables /sbin/ip6tables Multiple entries named 'sshusers' in /etc/group. Please fix this with pwck or grpck. useradd: failed to prepare the new /etc/group entry 'sshusers' chown: invalid user: ‘web282:client1’ chown: invalid user: ‘web282:client1’ finished.
Seemas as if your group file is corrupted. make a backup of the files /etc/passwd, /etc/shadow, /etc/group and /etc/gshadow. Then run the commands: pwck and grpck to check and repair the files.