Enable Microsoft Defender With PowerShell
On – PowerShell Set-MpPreference -DisableRealtimeMonitoring 0
Update definitions With PowerShell
We’re going first to clear your cache and then try to update manually.
Press the Windows Key + X and click on Windows PowerShell (Admin)
Copy and paste the following two lines one at a time followed by pressing the Enter key:
“%ProgramFiles%Windows DefenderMpCmdRun.exe” -removedefinitions -dynamicsignatures.
“%ProgramFiles%Windows DefenderMpCmdRun.exe” -SignatureUpdate.
Uninstall definitions updates
Open Start.
Search for Command Prompt, right-click the top result, and select the Run as administrator option.
Type the following command to open the antivirus tool location and press Enter:cd C:ProgramDataMicrosoftWindows DefenderPlatform4.18*
Type the following command to remove the most recent definitions and press Enter:MpCmdRun -RemoveDefinitions -AllThe -All option restores the previous definitions from the backup or original default set of signatures.
Type the following command to rollback the engine version and press Enter:MpCmdRun -RemoveDefinitions -EngineThe -Engine option rolls back to the previous version of the antivirus engine.
Type the following command to remove dynamic signature updates and press Enter:MpCmdRun -RemoveDefinitions -DynamicSignaturesThe -DynamicSignatures option uninstalls only the dynamic signatures.
After you complete the steps, the definitions will be removed from your computer according to your configuration.
How to check for updates on Microsoft Defender
Open Start.
Search for Command Prompt, right-click the top result, and select the Run as administrator option.
Type the following command to open the antivirus tool location and press Enter:cd C:ProgramDataMicrosoftWindows DefenderPlatform4.18*
Type the following command to check and update Microsoft Defender Antivirus and press Enter:MpCmdRun -SignatureUpdate
How to perform quick virus scan with Microsoft Defender
Open Start.
Search for Command Prompt, right-click the top result, and select the Run as administrator option.
Type the following command to open the antivirus tool location and press Enter:cd C:ProgramDataMicrosoftWindows DefenderPlatform4.18*
Type the following command to perform a quick antivirus scan and press Enter:MpCmdRun -Scan -ScanType 1Quick tip: You can also replace 1 with the 0 option in the command to start a default scan according to your configuration.
How to perform full virus scan with Microsoft Defender
Open Start.
Search for Command Prompt, right-click the top result, and select the Run as administrator option.
Type the following command to open the antivirus tool location and press Enter:cd C:ProgramDataMicrosoftWindows DefenderPlatform4.18*
Type the following command to perform a full antivirus scan and press Enter:MpCmdRun -Scan -ScanType 2