Convert warn verdict to block: registry value EnableConvertWarnToBlockComputerHKLM\Software\Policies\Microsoft\Windows Defender\NIS

Policy ID: EnableConvertWarnToBlock
Scope: Computer Configuration
Supported on: At least Windows Server 2016, Windows 10 Version 1709
Source: Administrative Templates (.admx) for Windows 11 2026 Update (26H2) (version 1.0)
Category: Windows Components › Microsoft Defender Antivirus › Network Inspection System

Registry

EnableConvertWarnToBlock

REG_DWORDComputer

HKLM\Software\Policies\Microsoft\Windows Defender\NIS Current key

Enabled value: 1
Disabled value: 0

Apply with .reg · CMD · PowerShell

.reg

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\NIS]

; Options (use only one)
; Enabled
"EnableConvertWarnToBlock"=dword:00000001
; Disabled
"EnableConvertWarnToBlock"=dword:00000000

CMD

:: Options (use only one)

:: Enabled
reg add "HKLM\Software\Policies\Microsoft\Windows Defender\NIS" /v "EnableConvertWarnToBlock" /t REG_DWORD /d 1 /f
:: Disabled
reg add "HKLM\Software\Policies\Microsoft\Windows Defender\NIS" /v "EnableConvertWarnToBlock" /t REG_DWORD /d 0 /f

PowerShell

# Common: create the key
New-Item -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\NIS' -Force | Out-Null

# Options (use only one)
# Enabled
New-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\NIS' -Name 'EnableConvertWarnToBlock' -PropertyType DWord -Value 1 -Force | Out-Null
# Disabled
New-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\NIS' -Name 'EnableConvertWarnToBlock' -PropertyType DWord -Value 0 -Force | Out-Null