Bringing multiple projects together in a WAP packaged solution for a self-contained WinUI Desktop app in .NET 8 causes DLL version issues with core DLLs

[JosHuybrighs]

I am investigating how I can migrate my current .NET6 WinUI/WinAppSDK package to .NET8. I decided to do the investigation by creating a simple self-contained Windows Desktop package with a WAP project to bundle a WinUI/WinSDKApp project and a WPF project. The reason for this is that this is what I am also doing in my .NET6 version. The WPF process is started at system boot and is kind of a background process to do things that are not possible with what is available in WinAppSDK.

Self-contained means that all the dlls of both apps are located in the same directory, which is fine because lots of them would otherwise appear twice in the package.

Doing the test I am confronted with an issue with the WindowsAppSDK framework (I am using 1.6.24114003) and the Microsoft.WindowsDesktop.App.WPF framework having different versions for some DLLs, like WindowsBase.dll (there are probably others but I didn't check that).

• In WinAppSDK the version is 8.01124.51707
• In WPF the version is 8.01124.52107

Version 8.01124.51707 ends up in the output directory.
No surprise: when the WPF app is launched there is an error that it can't find the expected WindowsBase.dll.

I can understand that there are some people who think that WinUI and WPF together in 1 package is weird. It however does solve the issue that if I need a long running process in the background (when the main app is not open) that only WPF (with a hidden window) allows me to gracefully shut it down or update it.
My current .NET6 solution doesn't have this problem but has an older Microsoft.WindowsDesktop.App framework where the dlls probably match with the ones in WinAppSDK.

Some questions therefore:

• Why are these 2 frameworks working with different versions of core dlls?
• Is this a temporary thing and do I have to be patient and wait till they align?
• With .NET8 still heavily worked on will these frameworks ever align?
• Is see this now with WPF but isn't this possible to happen with other type of projects added in the WAP project?
• Is there a workaround?

[mominshaikhdevs]

@manodasanW @Scottj1s