Definition Update for Windows Defender - KB2267602 (Definition 1.213.5087.0) - Error 0x80070643

This worked for me:  Run gpedit.msc if on Pro version, sort by path and look for Windows Defender. Go through and change from "Not Configured" to "Disabled".  In the second highlighted box, you'll want to "Enable". You'll notice the underlined red setting:

Specify the day of the week to check for definition updates. "Enabled" and change to "Never"

Reboot your machine and you should be good to go, this only works on the Pro version though.  You have to reboot as any attempting download will continue until you do so, even though it is disabled. 

When you open "Settings/Update & Security" you should see this:

"Some Settings are managed by your organization" in red which reflects what you just did in group policy.  All defender options are grayed out and inaccessible. 

If you ever want to re-enable Windows Defender, repeat the process in reverse, changing "Disabled" to "Not Configured" in the first yellow box and "Enabled" to "Not Configured" in the second yellow box.

One does kinda wonder at this stage where Microsoft are in all this. Thank you for your suggestion as that would finally seem to have solved my problem with updates and windows defender.

I uninstalled NIS several times and it fixed the problem, UNTIL I RE-INSTALLED NIS and there it was AGAIN....THE SAME "F*(**&*&**&&" PROBLEM!!! That GD error CONTINUES TO SHOW UP!!!  With all the "mental giants" that work for MS, one would THINK someone techie would SOLVE the problem. I know the answer WHEN will MS.....FIX IT???

DIDN'T WORK FOR ME!!!

As an alternative and even though Windows Defender is off, you can manually download the latest windows defender definitions here:

https://www.microsoft.com/security/portal/definitions/adl.aspx

Scroll down, midway through the page, select your OS and system architecture and download the file.  It is an *.exe file, run it as an administrator. You won't see it "do" anything but it will install current definitions with defender. Reboot. On the most stubborn systems where the error persists, despite the above method,  I've seen this solve the issue.