I installed cockpit with zypper in cockpit and got the same issue.
When I looked at the LOGs I see that the cockpit-ws User was not created.
I don’t really know why and how but if you want a quickfix it should be enough to create the user: sudo useradd -r -s /sbin/nologin cockpit-ws
After that you should start the cockpit.socket systemctl enable --now cockpit.socket
Finally you should reach the UI with: https://localhost:9090
I have this output on journal after doing the recommended above.
For cockpit socket:
Sep 29 17:02:56 localhost systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:02:56 localhost systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:03:19 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
Sep 29 17:08:15 192.168.88.179 systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:08:15 192.168.88.179 systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:08:20 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
Sep 29 17:09:06 192.168.88.179 systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:09:06 192.168.88.179 systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:09:10 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
Sep 29 17:15:35 192.168.88.179 systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:15:35 192.168.88.179 systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:15:48 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
Sep 29 17:38:42 192.168.88.179 systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:38:42 192.168.88.179 systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
For cockpit service:
Sep 29 17:39:21 192.168.88.179 systemd[1]: Starting Cockpit Web Service...
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22519]: cockpit.service: Failed to determine group credentials: No such process
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22519]: cockpit.service: Failed at step GROUP spawning /usr/lib/cockpit-certificate-ensure: No su>
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Control process exited, code=exited, status=216/GROUP
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Starting Cockpit Web Service...
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22522]: cockpit.service: Failed to determine group credentials: No such process
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22522]: cockpit.service: Failed at step GROUP spawning /usr/lib/cockpit-certificate-ensure: No su>
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Control process exited, code=exited, status=216/GROUP
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Starting Cockpit Web Service...
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22525]: cockpit.service: Failed to determine group credentials: No such process
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22525]: cockpit.service: Failed at step GROUP spawning /usr/lib/cockpit-certificate-ensure: No su>
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Control process exited, code=exited, status=216/GROUP
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Starting Cockpit Web Service...
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22528]: cockpit.service: Failed to determine group credentials: No such process
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22528]: cockpit.service: Failed at step GROUP spawning /usr/lib/cockpit-certificate-ensure: No su>
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Control process exited, code=exited, status=216/GROUP
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Starting Cockpit Web Service...
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22531]: cockpit.service: Failed to determine group credentials: No such process
Sep 29 17:39:21 192.168.88.179 (e-ensure)[22531]: cockpit.service: Failed at step GROUP spawning /usr/lib/cockpit-certificate-ensure: No su>
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Control process exited, code=exited, status=216/GROUP
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Start request repeated too quickly.
Sep 29 17:39:21 192.168.88.179 systemd[1]: cockpit.service: Failed with result 'exit-code'.
Sep 29 17:39:21 192.168.88.179 systemd[1]: Failed to start Cockpit Web Service.
Sep 29 17:59:26 192.168.88.179 systemd[1]: Starting Cockpit Web Service Socket...
Sep 29 17:59:26 192.168.88.179 systemd[1]: Listening on Cockpit Web Service Socket.
Sep 29 17:59:39 192.168.88.179 systemd[1]: cockpit.socket: Failed with result 'service-start-limit-hit'.
Sep 29 17:59:38 192.168.88.179 systemd[1]: Dependency failed for Cockpit Web Service.
Sep 29 17:59:38 192.168.88.179 systemd[1]: cockpit.service: Job cockpit.service/start failed with result 'dependency'.
Also when I add the user with your command above I have this output:
sudo useradd -u 104 -g 466 -c "User for cockpit web service" -d /nonexisting -s /sbin/nologin cockpit-ws
useradd: UID 104 is not unique