Windows 10: Cannot start windows defender

I am unable to start windows defender via the security center nor the services window


Looking at the event log (system) all I see is this:

The Windows Defender Antivirus Service service failed to start due to the following error:
The parameter is incorrect.

Try to start via services window has a slightly different error message:

Windows could not start the Windows Defender Antivirus Servie service on Local Computer. Error 87: The parameter is incorrect.

:)

 

window defender

• • • 
      You will want to print these instructions for offline reference -
      

IMPORTANT => DON'T SKIP ANY STEP perform all Steps in one uninterrupted session - If a Step says to reboot
reboot.

Problems starting Windows Defender in Windows 8/8.1/10

Pləase let us know what fixes the problem or if the pяoblem remains.

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Windows Defender Anitvirus

Hello,

There are multiple reasons why you are having issues, enabling Windows Defender. To assist you with your concern, you can refer to
PrashantKumar96's
Forum Article on how to fix Windows Defender not starting.

We suggest that you try the troubleshooting steps listed there, especially the number six troubleshooting step.

Let us know of the outcome.

Regards.

 

Windows Defender problem

Hi Ernst,

To troubleshoot this issue, we suggest that you check the Windows Defender service if it's running. If you are using a third party spyware/malware program, it may disable the Windows Defender service. To do this, please follow the steps below:

• Press Windows + R key.
• Type services.msc.
• Right-click Windows Defender service and click
  Start.

Let us know the result.