Microsoft Defender Antivirus Mini-Filter Driver - Windows 11 Service
Microsoft Defender Antivirus On-Access Malware Protection Mini-Filter Driver.
This service also exists in Windows 10 and 8.
Startup Type
| Windows 11 version | Home | Pro | Education | Enterprise |
|---|---|---|---|---|
| 21H2 | Boot | Boot | Boot | Boot |
| 22H2 | Boot | Boot | Boot | Boot |
| 23H2 | Boot | Boot | Boot | Boot |
| 24H2 | Boot | Boot | Boot | Boot |
Default Properties
| Display name: | Microsoft Defender Antivirus Mini-Filter Driver |
| Service name: | WdFilter |
| Type: | filesys |
| Path: | %WinDir%\system32\drivers\WdFilter.sys |
| Error control: | normal |
| Group: | FSFilter Anti-Virus |
Default Behavior
The Microsoft Defender Antivirus Mini-Filter Driver service is a file system driver. If Microsoft Defender Antivirus Mini-Filter Driver fails to start, the error is logged. Windows 11 startup proceeds, but a message box is displayed informing you that the WdFilter service has failed to start.
Dependencies
Microsoft Defender Antivirus Mini-Filter Driver is unable to start, if the FltMgr service is stopped or disabled.
Restore Default Startup Type for Microsoft Defender Antivirus Mini-Filter Driver
Automated Restore
1. Select your Windows 11 edition and release, and then click on the Download button below.
2. Save the RestoreMicrosoftDefenderAntivirusMiniFilterDriverWindows11.bat file to any folder on a local drive such as SSD or a hard disk.
3. Right-click the downloaded batch file and select Properties.
4. Check the Unblock checkbox and click OK.
5. Right-click the batch file again and select Run as administrator.
6. Restart the computer to save changes.
Note. Make sure that the WdFilter.sys file exists in the %WinDir%\system32\drivers folder. If this file is missing you can try to restore it from your Windows 11 installation media.