Microsoft Defender Antivirus update blocking downloads in Windows 10

Recently, Microsoft Defender Antivirus for Windows 10 received a new update, which brings the Antimalware Client Version to 4.18.2008.9. Due to a new file path in the update, Windows 10 is inadvertently blocking downloads when AppLocker is enabled.

Windows 10 antimalware platform update causes issues

“Because of a change in the file path location in the update, many downloads are blocked when AppLocker is enabled,” Microsoft explains.

If you want to fix the issue, open Group Policy Editor in Windows 10 > Change the setting to Allow for the following path:

%OSDrive%\ProgramData\Microsoft\Windows Defender\Platform\*

This update affects several Windows 10 components — Windows Defender Antivirus service (MsMpEng.exe), Network Realtime Inspection service (NirSrv.exe), and Windows Defender Antivirus drivers. The number of binary location changes includes the change in location for Windows Defender Antivirus service (MsMpEng.exe) and Network Realtime Inspection service (NirSrv.exe) components:

%ProgramData%\Microsoft\Windows Defender\Platform\

Here’s the updated location for Windows Defender Antivirus Drivers:

%Windir%\System32\drivers\wd

How to roll back this update

There are a couple of ways to roll back this update for the Microsoft Defender antimalware platform. Run the following command if you want to roll back this update to the previous version:

“%programdata%\microsoft\windows defender\platform\\mpcmdrun.exe” -revertplatform

Run the following command if you want to roll back this update to the Inbox CAMP version:

"%programfiles%\Windows Defender\MpCmdRun.exe" -resetplatform

This update will bring a change to the antimalware client version on the Windows 10 operating system (Enterprise, Pro, and Home editions), Windows Server 2019, and Windows Server 2016.

Microsoft Defender Antivirus antimalware platform update is available to targeted Windows 10 users via the Microsoft Update Catalog website, Windows Update, and Windows Server Update Services (WSUS).

Windows 10 users are advised to find the antimalware client version by opening the Windows Security app and navigating to the Windows Security app > Settings > About.

In related news, a recent update to Microsoft Defender Antivirus in Windows 10 brings a new capability, which allows users to download files from the web.