Security center is updating definitions for windows defender
Blocking or allowing apps and files before downloading them, protecting from malicious websites (when using Microsoft Edge) and checking downloads from Windows Store for malware can be configured from here.: Parental controls too are now integrated.Blocking specific websites (when using Edge), setting screen time, managing which apps and games can be downloaded as well as viewing a weekly activity report of online activity can be set from here.
Only one solution has worked so far: uninstall Norton, let the Defender update run then reinstall Norton. Obviously, Norton blocks the defender update and this leaves Windows update in a defective state.
These features now come under : This will automatically suggest if Windows updates are applied and updated, whether PC is running out of storage space and if there are any device driver conflicts.
Also, resetting PC can be done from here using the is also now a part of Windows Defender Security Center.
Actually it happens when a few system services required to run Windows Update are not running or a few system files are not registered properly.
Microsoft has acknowledged the issue in a KB article and provided a fix for it.