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WiX extensions and custom actions

WiX extends the functionality of Windows Installer by providing WiX Extensions that typically include compiler extensions to provide custom elements and attributes in your WiX authoring and custom actions to implement the extended functionality.

The following WiX extensions are provided by the WiX team:

WixToolset.BootstrapperApplications.wixextBal schema
WixToolset.ComPlus.wixextComplus schema
WixToolset.Dependency.wixextDependency schema
WixToolset.DifxApp.wixextDifxapp schema
WixToolset.DirectX.wixextDirectx schema
WixToolset.Firewall.wixextFirewall schema
WixToolset.Http.wixextHttp schema
WixToolset.Iis.wixextIis schema
WixToolset.Msmq.wixextMsmq schema
WixToolset.Netfx.wixextNetfx schema
WixToolset.PowerShell.wixextPowershell schema
WixToolset.Sql.wixextSql schema
WixToolset.UI.wixextUI schema
WixToolset.Util.wixextUtil schema
WixToolset.VisualStudio.wixextVs schema

Using extensions

To use a WiX extension during the build of your project, you need to load the extension and reference its namespace in your WiX authoring.

Loading extensions using the Wix.exe command-line tool

To use a WiX extension when using the Wix.exe command-line .NET tool, you need to:

  1. Add the extension to the WiX extension cache.
  2. Use the extension when building.

For example:

wix extension add -g WixToolset.Util.wixext
wix extension add -g WixToolset.BootstrapperApplications.wixext
wix build Bundle.wxs Bundle.en-us.wxl -ext WixToolset.Util.wixext -ext WixToolset.BootstrapperApplications.wixext

Loading extensions in a .wixproj MSBuild project

WiX extensions are available as NuGet packages on You can reference them as PackageReference items in your .wixproj MSBuild projects:

<PackageReference Include="WixToolset.BootstrapperApplications.wixext" />
<PackageReference Include="WixToolset.Util.wixext" />

You might need to specify a version for WiX extension packages (such as when they're prerelease packages):

<PackageReference Include="WixToolset.BootstrapperApplications.wixext" Version="5.0.1" />
<PackageReference Include="WixToolset.Util.wixext" Version="5.0.1" />

You need to restore package references. When using the dotnet build command, restore is automatic. When using .NET Framework MSBuild, you can use the -Restore switch on your msbuild command line to run package restore before building.

Declare the extension namespace

When you need to use a custom element from a WiX extension in your WiX authoring, you need to use the namespace of that extension. For example, the WixToolset.VisualStudio.wixext extension uses the namespace for its elements so to use the WixToolset.VisualStudio.wixext extension element FindVisualStudio, you might have authoring that looks like this:


<vs:FindVisualStudio />

<PropertyRef Id="VS2022_ROOT_FOLDER" />