When you visit Windows Update , you may receive one of the following error messages:
Digital Signatures are missing.
Page Cannot be Displayed.
The Page Requested Cannot be Displayed.Additionally, the %systemroot%\WindowsUpdate.log file may contain the following error message:
Why does it happen?
It happens if Vx2 ZServ malware is there.
Resolution:-See the resolution as described in the following Microsoft KB Article:-
Vx2 ZServ malware removal tool:-
Windows Defender (Beta 2)