Windows 10 Update causing Problem(s) yet again

 The fix to Windows Defender in Windows 10 fixed the problem it was to address (a signature file casing user triggered file system checks to abort) BUT the fix then caused user initiated file system checks to fail at a random time in the check. Users affected would note a less than thorough file system check.
 The fix will be fixed, yours may be fixed already.
 An issue with getting Windows Defender signature updates has been how do I  manually check and then download and apply the signature updates.
 This post will detail that process.

 Use the Search box  Virus and Threat Protections 

Virus and Threat Settings

The response

IF YOU ARE USING A SECURITY SUITE AND ITS SCANNING METHOD, YOU CAN ADD THE WINDOWS DEFENDER FILE SCANNING FOR DEFENSE IN DEPTH.