Windows 10 October 2018 Update rollout now paused

Maybe conflicts with Store updating some apps?

One of 3 definition update failure 10/23/2018

Interesting.

I played a hunch just now, but not sure if there is anything to it...

A few days ago we talked of compressing binaries to save disk space and I was curious and tried it. Since then I've been running things compressed. I've restored back to an image made before I compressed and find Defender updated OK.

Coincidence ? I've no idea but I might try further investigations later.

Stitch194 said:

One of 3 definition update failure 10/23/2018

This has been normal activity on my machine every time a Defender definition update and an antimalware platform update are found during the same Windows Update automatic check. The definition update fails, antimalware platform update goes in, definition then installs. Running Windows Update troubleshooter doesn't fix it. For me, this behavior started with 1803. I'm on 1809 now and it still happens.

kado897 said:

I was about to say that there was a platform update at the same time which usually causes a failure.

I would run into the same update issue on a regular basis, then I started using Windows Update Manager and the issue gets resolved as you can control the download/install process on an individual update basis. Look into the program. Great support and being actively developed. GitHub - DavidXanatos/wumgr: Windows update managemetn tool for windows 10

Why are Microsoft running definition updates for Defender through Windows Update anyway? Shouldn't it get updates through the platform instead, like any other anti-virus? Maybe that would alleviate some of the problems it's having in the update process.

Faith said:

Why are Microsoft running definition updates for Defender through Windows Update anyway? Shouldn't it get updates through the platform instead, like any other anti-virus? Maybe that would alleviate some of the problems it's having in the update process.

I've been wondering the same thing for years. Defender's updating is puzzling -- it's once per day via WU auto check, but, if it updates on its own without a WU auto check, it still uses the WU mechanism. MS pushes Defender as a viable antivirus and I should think it should behave as one. Every third-party antivirus I know of will update through the platform every time a computer is on and new definitions come in. Defender doesn't check as often as they do and frequently, any number of definitions could be coming down before it does its thing.

And, FWIW, many people still have the 0x2 error for Defender automatic scans. That dates back to the Anniversary Update and MS has never fixed it. They just tell people to create their own scan task.