[c#] How to add System.Windows.Interactivity to project?

My project missing System.Windows.Interactivity. Google says that I have to install Expression Blend, but on my other computer I have this library and I don't have Expression Blend installed. So there should be another way to obtain System.Windows.Interactivity? What should I do? (right now i don't have another computer so I can not just copy this library :)

With Blend for Visual Studio, which is included in Visual Studio starting with version 2013, you can find the DLL in the following folder:

C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.5\Libraries

You will have to add the reference to the System.Windows.Interactivity.dll yourself though, unless you use Blend for Visual Studio with an existing project to add functionality that makes use of the Interactivity namespace. In that case, Blend will add the reference automatically.

I have had the exact same problem with a solution, that System.Windows.Interactivity was required for one of the project in Visual Studio 2019, and I tried to install Blend for Visual Studio SDK for .NET from Visual Studio 2019 Individual components, but it did not exist in it.

The consequence of that, I was not able to build the project in my solution with repetitive of following similar error on different XAML parts of the project:

The tag 'Interaction.Behaviors' does not exist in XML namespace 'clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity'.

The above mentioned errors snapshot example

The solution, the way I solved it, is by installing Microsoft Expression Blend Software Development Kit (SDK) for .NET 4 from Microsoft.

Thanks to my colleague @felza, mentioned that System.Windows.Interactivity requires this sdk, that is suppose to be located in this folder:

C:\Program Files (x86)\Microsoft SDKs\Expression\Blend\.NETFramework\v4.0

In my case it was not installed. I have had this folder C:\Program Files (x86)\Microsoft SDKs with out Expression\Blend\.NETFramework\v4.0 folder inside it.

After installing it, all errors disappeared.

I got it via the Prism.WPF NuGet-Package. (it includes Windows.System.Interactivity)

Sometimes, when you add a new library, in introduces a clashing version of System.Windows.Interactivity.dll.

For example, the NuGet package MVVM light might require v4.2 of System.Windows.Interactivity.dll, but the NuGet package Rx-XAML might require v4.5 of System.Windows.Interactivity.dll. This will prevent the the project from working, because no matter which version of System.Windows.Interactivity.dll you include, one of the libraries will refuse to compile.

To fix, add an Assembly Binding Redirect by editing your app.config to look something like this:

<?xml version="1.0"?>
<configuration>
<runtime>
  <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
    <dependentAssembly>
      <assemblyIdentity name="System.Windows.Interactivity"
                        publicKeyToken="31bf3856ad364e35"
                        culture="neutral"/>
      <bindingRedirect oldVersion="4.0.0.0"
                       newVersion="4.5.0.0" />
    </dependentAssembly>
  </assemblyBinding>
</runtime>
<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5"/></startup>
<appSettings>
  <add key="TestKey" value="true"/>
</appSettings>

Don't worry about changing the PublicKeyToken, that's constant across all versions, as it depends on the name of the .dll, not the version.

Ensure that you match the newVersion in your appConfig to the actual version that you end up pointing at:

If you are working with MVVM Light you have to use the System.Windows.Interactivity Version 4.0 (the NuGet .dll wont work) that you can find under :

PathToProjectFolder\Software\packages\MvvmLightLibs.5.4.1.1\lib\net45\System.Windows.Interactivity.dll

Just add this .dll manually as Reference and it should be fine.

Although this issue is quite old, i think this is relevant news / the most recent answer: Microsoft open-sourced XAML Behaviours and posted a blog post how to update to this version: https://devblogs.microsoft.com/dotnet/open-sourcing-xaml-behaviors-for-wpf/

To save you a click, this is the main steps to migrate:

1. Remove reference to “Microsoft.Expression.Interactions” and “System.Windows.Interactivity”
2. Install the Microsoft.Xaml.Behaviors.Wpf NuGet package.
3. XAML files – replace the xmlns namespaces http://schemas.microsoft.com/expression/2010/interactivity and http://schemas.microsoft.com/expression/2010/interactions with http://schemas.microsoft.com/xaml/behaviors
4. C# files – replace the usings in c# files “Microsoft.Xaml.Interactivity” and “Microsoft.Xaml.Interactions” with “Microsoft.Xaml.Behaviors”

Alternative solution is to modify your current Visual Studio installation in the Visual Studio Installer

Win+R %ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vs_installer.exe

adding the Blend for Visual Studio SDK for .NET 'Individual component' under 'SDKs, libraries, and frameworks':

after adding this component System.Windows.Interactivity should appear in its regular location Add Reference/Assemblies/Extensions.

It appears this would only work for VS2017 or earlier. For later versions, please refer to other answers.

The easiest way might be to get it from NuGet:

http://www.nuget.org/packages/System.Windows.Interactivity.WPF/

It's in MVVM Light, get it from the MVVM Light Download Page.

There is a new NuGet package that contains the System.Windows.Interactivity.dll that is compatible with:

• WPF 4.0, 4.5
• Silverligt 4.0, 5.0
• Windows Phone 7.1, 8.0
• Windows Store 8, 8.1

To install Expression.Blend.Sdk, run the following command in the Package Manager Console

PM> Install-Package Expression.Blend.Sdk

http://www.nuget.org/packages/Expression.Blend.Sdk/