[Bug] Cannot compile Windows MAUI .NET 9 project when referencing Microsoft.Identity.Client.Desktop

[superwilly1]

Library version used

4.66.2

.NET version

.NET 9 MAUI

Scenario

Other - please specify

Is this a new or an existing app?

The app is in production, and I have upgraded to a new version of MSAL

Issue description and reproduction steps

Today we updated our MAUI app from .NET 8 to .NET 9.
Android and iOS are fine, but Windows does not work with the Microsoft.Identity.Client.Desktop package.
The app cannot compile, showing these error messages:
Cannot resolve Assembly or Windows Metadata file 'Type universe cannot resolve assembly: System.Xaml, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089.'
and:
Could not copy the file "C:\temp\NET9MAUIWindowsIssue\obj\Debug\net9.0-windows10.0.19041.0\win10-x64\Platforms\Windows\App.xbf" because it was not found.

These errors also occur in a file->new->MAUI project, and only adding the package reference.
No code changed in the new MAUI app, only added the package reference.
See the example project in the attached zipfile:
NET9MAUIWindowsIssue.zip

Only the Desktop package is an issue, these packages work:

<PackageReference Include="Microsoft.Identity.Client" Version="4.66.2" />
<PackageReference Include="Microsoft.Identity.Client.Extensions.Msal" Version="4.66.2" />

Relevant code snippets

Only change needed to reproduce is to add this to the .csproj file (of an empty new .NET MAUI project), referencing the NuGet package:

<ItemGroup Condition="$(TargetFramework.Contains('-windows'))">
	<PackageReference Include="Microsoft.Identity.Client.Desktop" Version="4.66.2" />
</ItemGroup>

Expected behavior

The app should compile (and work) on .NET9, like it also used to work on .NET8.

Identity provider

Microsoft Entra ID (Work and School accounts and Personal Microsoft accounts)

Regression

No response

Solution and workarounds

No solution or workaround as of yet.

[kittykmartin]

we also have exsactly the same as usual a MAUI upgrade nightmare

[nicop85]

Same problem here. This is urgent since without that users aren't able to perform logins in my App

[kittykmartin]

Yep I don't have a solution yet still working on it

…

On Fri, 15 Nov 2024, 19:30 nicop85, ***@***.***> wrote: Same problem here. This is urgent since without that users aren't able to perform logins in my App — Reply to this email directly, view it on GitHub <#4993 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BBTUC66F7F7KX2MTOS33EC32AZDXFAVCNFSM6AAAAABRXBOE2OVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDINZZG43TMNZQG4> . You are receiving this because you commented.Message ID: <AzureAD/microsoft-authentication-library-for-dotnet/issues/4993/2479776707 @github.com>

[PureWeen]

I don't think this is a .NET MAUI issue

I was able to reproduce here on a WinUI app that doesn't use MAUI

App11.zip

[Maxxelemel]

Thank you,
Do we think it's a .net 9 thing then?