Windows Defender Update Causes Boot and Download Problems

A new update for Microsoft’s security program “Windows Defender” is currently causing numerous problems. This prevents some Windows 10 computers from booting and causes download problems.

The startup problems occur on Windows 10 systems where the so-called secure boot is enabled. These PCs can no longer be started due to the update. Microsoft has already been informed about the problem and presented a solution proposal to those affected. However, this is anything but comfortable, as the administrators have to go into the BIOS/UEFI to get the PC started again. The following command must be entered there:

"%programdata%\Microsoft\Windows Defender\Platform\4.18.1901-7\MpCmdRun.exe" -revertplatform

Microsoft then recommends that you wait a few minutes. The success of this intervention can be checked by entering the following commands:

sc query windefend
sc qc winding

The system should then no longer specify version 4.18.1901.7 as active. The PC can then be restarted normally. Entering these commands switches off the Secure-Boot, thus taking away some of the security. However, Microsoft states that Secure-Boot can be reactivated in the BIOS/UEFI afterwards.

Other problems with the update are related to the AppLocker. This prevents numerous downloads since the update. The reason for this is the change of a file path by the update. The problem can be solved by adjusting the changed path in the AppLocker settings. The following path must be changed:

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