D-Bus issues

The issue

D-Bus is how the Supervisor does most of the communication with the host, without this, multiple things that the Supervisor needs to do will fail.

The solution

If the D-Bus daemon is not running, start it.

If that does not help, reboot your operating system.

As a last resort, you need to reinstall the host running the Supervisor with one of the supported operating systems, see instructions here.