


I rebooted afterward, which probably wasn’t necessary, ran WindowsUpdate and it downloaded the Definition Updates without issue. "%PROGRAMFILES%\Windows Defender\MPCMDRUN.exe" -SignatureUpdate "%PROGRAMFILES%\Windows Defender\MPCMDRUN.exe" -RemoveDefinitions -All Open an elevated Command Prompt and run the following two commands. After putting my Googling skills to work I found this forum post that had a quick fix that did the trick. I did the normal WindowsUpdate troubleshooting steps of deletion of the Download folder, reboot, etc., but nothing seemed to work. Definition Update for Windows Defender – KB2267602 – Error 0x80070643 The Definition numbers will change but the KB stays the same. After researching this a bit I found that Microsoft is using the same KB2267602 for every Windows Defender Definition Update. It failed with the following Error 0x80070643 numerous times. Building a Windows 10 image for a Horizon View deployment I found Windows Update stuck on this Definition Update for Windows Defender.
