Decompiling WPF Applications

This guide explains how to fix common compilation issues when decompiling WPF applications using tools like ILSpy or dnSpy.

Step 1: Create a New WPF Project

Create a new WPF application project in Visual Studio. Name it something like DecompiledWpfApp.

Step 2: Load the Executable

Open ILSpy and drag your target .exe file into the application. Navigate to the assembly you want to decompile.

Step 3: Export the Code

Click File → Save Code... to generate the source code to you're desired location.

Step 4: Add Required Assemblies

Compile the project initially. You will likely encounter errors due too missing WPF assemblies. Add the following references:

• WindowsBase.dll
• PresentationCore.dll

After adding these assemblies, the project should compile successfully.

Step 5: Restore XAML Files

Locate the MainWindow.xaml file in your decompiled output. Add it to your project directory and modify the code-behind file from MainWindow.cs to MainWindow.xaml.cs to match WPF conventions.

Extract the content from mainwindow.baml and paste it into the newly added MainWindow.xaml file.

Step 6: Clean Up MainWindow.xaml.cs

Remove unnecessary auto-generated members from the decompiled code. Add the partial modifier to the MainWindow class declaration.

Remove these unwanted items:

[GeneratedCode("PresentationBuildTasks", "4.0.0.0")]
internal TextBlock textBlock1;

private bool _contentLoaded;

public void InitializeComponent()

void IComponentConnector.Connect

Your class should look like this:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }
}

Step 7: Clean Up App.xaml.cs

Apply the same cleanup to App.xaml.cs. Add the partial modifier and remove extraneous generated attributes:

[GeneratedCode("PresentationBuildTasks", "4.0.0.0")]
public void InitializeComponent()

Step 8: Remove BAML Files

Delete the mainwindow.baml file from your project as it is no longer needed.

Common Error Solutions

Error 1: Style Property Resolution

Problem: Cannot resolve Style Property "Template". Ensure you own the type or use Class.Property syntax.

Solution: Change <Setter Property="Template"> to <Setter Property="Control.Template">

Error 2: No Available Project Items

Problem: When adding new items via Solution Explorer, no project templates appear.

Solution: This typically occurs due to incorrect ProjectTypeGuids in the project file. Compare with a valid WPF project and update accordingly:

<ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>

Note: The GUID must use uppercase letters. Decompiled projects often contain lowercase GUIDs, which prevents WPF project functionality.

Error 3: Missing Main Method

Problem: Compilation error: Program does not contain a static 'Main' method suitable for an entry point.

Soltuion: Update the project file to properly configure the application definition. Find:

<Page Include="App.xaml">
  <Generator>MSBuild:Compile</Generator>
  <SubType>Designer</SubType>
</Page>

Replace with:

<ApplicationDefinition Include="App.xaml">
  <Generator>MSBuild:Compile</Generator>
  <SubType>Designer</SubType>
</ApplicationDefinition>

This configuration generates the required Main method automatically.

Error 4: Missing LocalizedStrings

Problem: Compilation error: The type or namespace name 'LocalizedStrings' does not exist in the clr-namespace.

Solution: First, restart Visual Studio. If the error persists, clean the solution, close Visual Studio, and rebuild.

If issues continue:

1. Close Visual Studio
2. Navigate to: %LOCALAPPDATA%\Microsoft\Phone Tools\CoreCon\
3. Delete contents of folders: 10.0 and 11.0

Error 5: Main Window Not Displaying

Problem: Application runs but main window does not appear.

Solution: Configure the StartupUri property in App.xaml to specify the startup window:

<Application StartupUri="MainWindow.xaml" ...>