Migrate from UWP to the Windows App SDK

If you're happy with your current functionality in the Universal Windows Platform (UWP), then there's no need to migrate your project type. WinUI 2.x, and the Windows SDK, support UWP project types.

But if you've decided to migrate your app from UWP to the Windows App SDK, then in most cases your UI code needs just a few namespace changes. Much of your platform code can stay the same. You'll need to adjust some code due to differences between UWP apps and desktop apps. But we expect that for most apps (depending on codebase size, of course), migration will take on the order of days rather than weeks.

At a high level, these are the steps for migrating manually (but see the next section for info about using the .NET Upgrade Assistant tool):

1. Create a new WinUI 3 packaged desktop project (see Create your first WinUI 3 project). That could go into your existing solution.
2. Copy your XAML/UI code. In many cases you can simply change namespaces (for example, Windows.UI.* to Microsoft.UI.*).
3. Copy your app logic code. Some APIs need tweaks, such as Popup, Pickers, and SecondaryTiles.

For full details, see the topics in the table below. They describe and demonstrate how to manually migrate your Universal Windows Platform (UWP) application to the Windows App SDK.

Take particular note of What's supported when migrating from UWP to WinUI 3. That topic describes any functionality that's not yet supported in WinUI 3 and the Windows App SDK. If your app needs any of those features/libraries, then consider waiting to migrate.

Migrating by using the .NET Upgrade Assistant tool

As a further step in assisting you to migrate your UWP apps to the Windows App SDK and WinUI 3, we've leveraged the .NET Upgrade Assistant, adding support for migrating C# UWP apps. The UWP support automates much of the migration process. For more info, see the topic Migrate from UWP to the Windows App SDK with the .NET Upgrade Assistant.

Topics in this section

Topic	Description
Overall migration strategy	Considerations and strategies for approaching the migration process, and how to set up your development environment for migrating.
Mapping UWP features to the Windows App SDK	This topic compares major feature areas in the different forms in which they appear in UWP and in the Windows App SDK.
What's supported	Learn what features are currently available in WinUI 3 Desktop to evaluate whether you should attempt migrating your UWP app today.
Mapping UWP APIs and libraries to Windows App SDK	This topic provides a mapping of UWP APIs and libraries to their Windows App SDK equivalents.
Feature area guides	A collection of migration guidance topics, each focusing on a specific feature area.
Case study 1—PhotoLab (C#)	This topic is a case study of taking the C# UWP PhotoLab sample app, and migrating it to the Windows App SDK.
Case study 2—Photo Editor (C++/WinRT)	This topic is a case study of taking the C++/WinRT UWP Photo Editor sample app, and migrating it to the Windows App SDK.
Additional migration guidance	This topic contains additional migration guidance not categorized into a feature area in the feature area guides.
Migrate from UWP to the Windows App SDK with the .NET Upgrade Assistant	The .NET Upgrade Assistant is a command-line tool that can assist with migrating a C# UWP app to a Windows UI Library (WinUI) 3 app that uses the Windows App SDK.