Prevent access to 16-bit applications
Verified with Windows 11 25H2 — updated on July 30, 2026
Supported on: At least Windows Server 2003
Path in the GPO console
Computer Configuration\Administrative Templates\Windows Components\Application Compatibility Description
Specifies whether to prevent the MS-DOS subsystem (ntvdm.exe) from running on this computer. This setting affects the launching of 16-bit applications in the operating system. You can use this setting to turn off the MS-DOS subsystem, which will reduce resource usage and prevent users from running 16-bit applications. To run any 16-bit application or any application with 16-bit components, ntvdm.exe must be allowed to run. The MS-DOS subsystem starts when the first 16-bit application is launched. While the MS-DOS subsystem is running, any subsequent 16-bit applications launch faster, but overall resource usage on the system is increased. If the status is set to Enabled, the MS-DOS subsystem is prevented from running, which then prevents any 16-bit applications from running. In addition, any 32-bit applications with 16-bit installers or other 16-bit components cannot run. If the status is set to Disabled, the MS-DOS subsystem runs for all users on this computer. If the status is set to Not Configured, the OS falls back on a local policy set by the registry DWORD value HKLM\System\CurrentControlSet\Control\WOW\DisallowedPolicyDefault. If that value is non-0, this prevents all 16-bit applications from running. If that value is 0, 16-bit applications are allowed to run. If that value is also not present, on Windows 10 and above the OS will launch the 16-bit application support control panel to allow an elevated administrator to make the decision; on windows 7 and downlevel, the OS will allow 16-bit applications to run. Note: This setting appears in only Computer Configuration.
Registry
Software\Policies\Microsoft\Windows\AppCompat Value name: VDMDisallowed
Enabled: VDMDisallowed = 1
Disabled: VDMDisallowed = 0
MDM / Intune (CSP)
./Device/Vendor/MSFT/Policy/Config/ADMX_AppCompat/AppCompatPrevent16BitMach Microsoft Learn documentation Mapping data: Microsoft Learn (CC BY 4.0)
Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Prevent access to 16-bit applications
; State: Enabled
; Supported on: At least Windows Server 2003
[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\AppCompat]
"VDMDisallowed"=dword:00000001More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
$path = 'HKLM:\Software\Policies\Microsoft\Windows\AppCompat'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'VDMDisallowed' -Value 1 -Type DWordIntune XML
OMA-URI: ./Device/Vendor/MSFT/Policy/Config/ADMX_AppCompat/AppCompatPrevent16BitMach
Data type: String
Value:
<enabled/>Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows\AppCompat' -Name 'VDMDisallowed' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
$path = 'HKLM:\Software\Policies\Microsoft\Windows\AppCompat'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'VDMDisallowed' -Value 1 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\Software\Policies\Microsoft\Windows\AppCompat' -Name 'VDMDisallowed' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Prevent access to 16-bit applications
# State: Enabled
# Supported on: At least Windows Server 2003
$path = 'HKLM:\Software\Policies\Microsoft\Windows\AppCompat'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'VDMDisallowed' -Value 1 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.