Windows Defender KB4052623 impossible to install, error 0x80070643

Hi!

As the title says, I can't install KB4052623 from Windows Update, it fails with 0x80070643. I have tried reinstalling the OS, same problem.

Tried all the linked solutions, none of them worked. Is there any way to skip that update, if it's impossible to install it?

Finally I managed it to install. Set the date forward a year (2019), then checked for updates in Defender itself, it said the service has stopped. After that, clicked on install at Windows Update in settings app, and it installed the update without error.

Finally solved this annoying problem forever without a windows reinstall.

KB4052623 is the complete Windows Defender program package. It is now 2021 and I still had a 2019 version that didn't update.
This Defender program is located at C:\ProgramData\Microsoft\Windows Defender\Platform in a subfolder with its version number.
Given by the registry HKLM\SOFTWARE\Microsoft\Windows Defender\InstallLocation
The old version from 2019 was 4.18.1911.3-0 and after succesful install today it is 4.18.2103.7-0

The cause in my case: I use a RAM drive (R:) and set all TEMP/TMP environment variables to R:\TEMP but somehow this KB4052623 update doesn't like that!

I downloaded the latest KB4052623 file https://www.catalog.update.microsoft...px?q=KB4052623 (only one of the 3 is for your system) and installed it without problems AFTER setting all TEMP/TMP variables to %SystemRoot%\temp again.

I hope someone will find this useful.

Cheers

IIRC, that's the same error code I would get with probably 1909, when updating Windows 10, when there's also another update, seems to just mean that the update was cancelled, because of another update.

IIRC, never that error code for the CU, but believe it was probably the Windows Defender update, every time.
Then it updates like nothing was wrong, IIRC.

Seemed like it stopped occurring for me, starting with 2004.