Windows Defender service won’t start on Windows 10 [FIX]

By: Madeleine Dean
2 minute read

Windows Defender is one of the most popular antivirus programs worldwide, protecting millions of computers against vicious threads. However, sometimes starting Windows Defender proves to be a very difficult, as many users report.

Often, when users try to start Microsoft’s built-in antivirus, an error message appears on the screen informing them that the service couldn’t be started.

Windows Defender service won’t start

Here’s how one user describes this issue:

I am having issue with Windows Defender on windows 10. When I start it , it shows “service couldn’t be started” pop-up.
and when I try to start it from services in task manager it again shows a pop-up which says:
“windows cannot verify the digital signature for the drivers required for this file. A recent hardware or software change might have installed a file that signed incorrectly or damaged, or that might be malicious from an unknown source”

How to fix Windows Defender service start issues

1. Disable and remove third-party antivirus solutions

Running two antivirus solutions at the same time causes various technical issues. Use a dedicated software removal tools to completely remove any third-party antivirus files. Restart your Windows 10 computer and start Windows Defender again.

2.  Install the latest Windows Updates 

If there are any pending Windows updates, install them first and then try to update Windows Defender. Many users confirm that this simple action solves the majority of Windows Defender Update issues. Once you’ve installed the latest OS updates, restart your computer and try to update your antivirus.

3. Run a SFC scan

The Windows Defender service may not start due to file corruption issues. Run a System File Check to detect and repair corrupted files.

Type cmd in the Search box > select Command Prompt (run as admin) > type the following command in Command Prompt: sfc /scannow. Wait for the scan process to complete.

4. Clean your registry

If your system files are corrupted, Windows Defender may not be able to start or download and install the latest updates. If you want to quickly scan and repair your registry, install one of these registry cleaners on your computer.


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