This can happen when there was a network issue during the startup of the Supervisor.
Manually update the Supervisor. This can be done from the Configuration panel. On the card for “Supervisor”, there is a button to update the Supervisor.
This can also be done with the CLI, by running the following command:
ha supervisor update
In case this doesn’t work. Check the logs, if there’s an error where a host can’t be resolved (eg: lookup ghcr.io: no such host) there might be a problem with your network settings (eg: dns server that can’t be reached).