Today, we came around with another issue while turning on Windows Defender. As you can see in the image, the error prompt states that the Windows Defender service has malfunctioned.

Error 0x80070422 – The Service Couldn’t Be Started

The first thing to do is open the Services Manager, and check if the Windows Defender service is set to Automatic and Started. If it is not, then see if you can start it. Alternatively, you may find that the Windows Defender service is grayed out in Services Manager.  If you’re a victim of this issue, you’ll find that possibly, its due to some registry corruption. This can be fixed with selective steps described below, as per the suggestions made here.

  1. Press Windows Key + R combination, type put Regedt32.exe in Run dialog box and hit Enter to open the Registry Editor.

  2. Navigate to the following location:

  3. Firstly, take full ownership of WinDefend key. After taking ownership, in the right pane of this location, look for the DWORD named Start. Since you’re facing the issue, it must be having its Value data as 4 and by default, its Value data should remain 2. Differences in the Value data resulted in this happening. So in order to fix it, double click on the same DWORD to get this:

  4. In the above box, replace the Value data from 4 to 2. Click OK. You may close the Registry Editor now and try to enable Windows Defender protection. It should work fine by now.

Hope this helps! Similar error code posts:

Windows Update error 0x80070422WslRegisterDistribution failed with error: 0x80070422Activation Error 0x80070422Xbox App sign-in error (0x409) 0x80070422.