This is a common error generated by Windows Defender when the Windows Defender Service cannot be started. The fix is rather straight forward…
Go to Start -> Run Type in services.msc
Make sure Windows Defender Services is running, if it is not, manually start it.
If that doesn’t fix the problem, download and install Windows Defender from Microsoft.
If you are trying to Disable Windows Defender, follow this URL below…

{ 2 comments… read them below or add one }
thank u very much. it fixed my long time problem. cheers!!
I’m a Chinese Users,I just have the same problem and can’t settle it.Do you have any solutions?