After an update, if a core service fails to start, potential causes include dependencies, authentication, or incomplete updates:

The server requires another reboot to complete the rollback (A): Some updates require multiple reboots, but if rolling back did not resolve the issue, a missing dependency is more likely.

The administrator is not authorized to run the service (B): If the administrator previously had access and the update broke the service, it is likely due to software conflicts rather than permissions.

The server requires further updates of other software components (C): Many services rely on dependent libraries, drivers, or patches. If an update replaces or removes a necessary component, the service may fail until additional updates are applied.

The account used to run the service has expired (D): Expired accounts usually cause authentication failures but not outright service crashes unless explicitly required for the update process.

Since rolling back the update did not fix the issue, the most likely reason is that additional updates or dependencies are missing.