MS Article ID: 923159 "How to manually download the latest definition updates for Windows Defender".

Manually download Windows Defender Definition updates from the Microsoft Malware Protection Center Portal or from this direct download link (32-bit).
Double-click the Mpas-fe.exe file to install, then click OK.

Hi there, neat thanks!

no just click the arrow down on the help menu and check for updates

Louismjj,
Sometimes updating from within a program, as you suggested, doesn't work.
In that case, it has to be done manually.
That's what this topic is about, as the title indicates:

How To Manually Update Windows Defender Definitions

Hello,

My name is Jeannie. I am having a problem with my computer and the download of the lasest update for Windows Defender. I tried the manual way also and still got this error 0x80070643. Please help me!

Thank you,
Jeannie