Windows 10 – Windows Update stuck on failed Windows Defender Definition Update


Building a Windows 10 image for a Horizon View deployment I found Windows Update stuck on this Definition Update for Windows Defender.  It failed with the following Error 0x80070643 numerous times.  After researching this a bit I found that Microsoft is using the same KB2267602 for every Windows Defender Definition Update.  The Definition numbers will change but the KB stays the same.

Definition Update for Windows Defender – KB2267602 – Error 0x80070643


I did the normal WindowsUpdate troubleshooting steps of deletion of the Download folder, reboot, etc., but nothing seemed to work.  After putting my Googling skills to work I found this forum post that had a quick fix that did the trick.

Open an elevated Command Prompt and run the following two commands.

I rebooted afterward, which probably wasn’t necessary, ran WindowsUpdate and it downloaded the Definition Updates without issue.  These commands flush the existing Windows Defender Definitions and forces it to start from scratch.  Apparently the definition updates can and will get hung up or corrupted occasionally and need to be flushed.

This particular image didn’t need the customers preferred Anti-virus/Anti-malware software installed.  Normally I recommend using something other than Windows Defender.  Personally I like Bitdefender quite a bit.  For the home users reading this they have a pretty good and lightweight Free version available.

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