Build 19042.906 and 19043.906 are available in RPC and Beta Channel

Confirm exact issue with a Defender update last night. Couple reboots and it finally resolved itself and installed the definition update.

You could also try kick starting it by manually installing def update:

https://www.microsoft.com/en-us/wdsi/defenderupdates

@EddieL [MSFT]. 

Hi Eddie,

Could you check what is happening with this problem?

Thanks

https://aka.ms/AAbofsf

New CU's are available together with new Feature Experience Pack.

Releasing Windows 10 Build 19042.906 (20H2) to Release Preview Channel | Windows Insider Blog

The installer is broken. It stops at 20% & then it fails to install.

Confirm exact issue with a Defender update last night. Couple reboots and it finally resolved itself and installed the definition update.

You could also try kick starting it by manually installing def update:

https://www.microsoft.com/en-us/wdsi/defenderupdates

Thanks Johnny, 

I did several restarts for over an hour and nothing changed, the same defender update downloaded and installed fine on current public build.

I now just checked for updates directly from defender and that did the trick, after posting an error message that the service stopped, it was too fast to clear the error message and I could not get the snip of it. :-(.

It is not showing in update history, because it was updated directly from defender. We'll see what happens on next update :-)

Here's another one for you to check, completed at 20%:

Dism /Online /Cleanup-Image /StartComponentCleanup