Windows Defender Mini-Filter Driver (WdFilter) Service Defaults in Windows 8

Windows Defender On-Access Malware Protection Mini-Filter Driver.

Default Settings

Startup type:Boot
Display name:Windows Defender Mini-Filter Driver
Service name:WdFilter
Service type:filesys
Error control:normal
Group:FSFilter Anti-Virus
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WdFilter

Default Behavior

The Windows Defender Mini-Filter Driver service is a file system driver. In Windows 8 it is being loaded by Boot Loader before Kernel initialization. If Windows Defender Mini-Filter Driver fails to start, the error details are added to Windows 8 error log. When the operating system startup is complete, the user is being notified that the WdFilter service hasn't been started.


Windows Defender Mini-Filter Driver can't start, if the FltMgr service is disabled or not available.

Restore Default Startup Configuration for Windows Defender Mini-Filter Driver

1. Select your Windows 8 edition and update pack, and then click Download.

2. Save the Win8_WdFilter_Service_Startup.cmd file to a local storage device.

3. Run the saved file as an administrator.

4. Restart the computer.

The WdFilter service is using the WdFilter.sys file that is located in the %WinDir%\system32\drivers folder. If the file is corrupted or deleted, you can put it back in there.