Policy
Prevent access to 16-bit applications
Microsoft Windows
Policy overview
Key metadata and intent for this policy.
Supported OS tags: Windows10, Windows10RT, Windows11, Windows7, Windows8, Windows81, WindowsRT, WindowsRT81, WindowsServer2003, WindowsServer2008, WindowsServer2012, WindowsServer2012R2, WindowsServer2016, WindowsVista
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 values
How enabled and disabled states update the registry.
| Scope | Registry location | Type | Enabled value | Disabled value | Copy |
|---|---|---|---|---|---|
| Computer | Path Software\Policies\Microsoft\Windows\AppCompat Value name VDMDisallowed | REG_DWORD | HKLM 1 | HKLM 0 |
Policy elements
Inputs and configuration options exposed by this policy.
This policy has no additional user input fields.