Did you receive the 8050800C error from Windows update while trying to get the Windows Defender updates? I did with my Windows 7 Pro 64. Lots of sites tell a lot of stupid things to try, things that are only there to make the site catch more Google hits to serve more ads. Nobody seems to test their stuff anymore. I did. And I have a working, tested solution.
Executive summary of fix:
- Download the the Windows Defender update file manually (mpas-fe.exe, available from https://www.microsoft.com/en-us/wdsi/definitions )
- Start Windows in safe mode
- Run the downloaded exe in safe mode and reboot (or optionally run the exe with Windows Update Service disabled)
- It’s fixed!
For more details and illustrated guide, read more below.