[Bug] Maui Essentials WebAuthenticator not working in WinUI

I’m attempting to use WebAuthenticator in Maui Essentials to authenticate a WinUI project, but it’s having an issue finding the manifest file. It throws an exception saying:

Could not find file ‘C:\WINDOWS\system32\AppxManifest.xml’.

If I add a local version of https://github.com/dotnet/maui/blob/main/src/Essentials/src/WebAuthenticator/WebAuthenticator.uwp.cs into my project (I made PlatformAuthenticateAsync public to test it and just passed the url and callbackUrl in the WebAuthenticatorOptions) and adjust line 51 to:

var doc = XDocument.Load($"{AppDomain.CurrentDomain.BaseDirectory}AppxManifest.xml", LoadOptions.None);

It then finds the file, however, a new error is thrown that says:

System.Runtime.InteropServices.COMException: ‘There are no remote procedure calls active on this thread. (0x800706BD)’

Additionally, I set the CallbackUrl to:

new Uri("io.identitymodel.native://callback")

and the Url to:

new Uri("https://demo.identityserver.io")

• https://github.com/microsoft/WindowsAppSDK/issues/441

[shv07]

@jayveedee I was able to fix that error by setting Exported = true in the Activity class. You get this information if you see the build logs after setting it to more verbose from the VS settings.

My final Activity was like this:-

// MainActivity.cs
[Activity(NoHistory = true, LaunchMode = LaunchMode.SingleTop, Exported = true)] 
[IntentFilter(new[] { Android.Content.Intent.ActionView },
        Categories = new[] { Android.Content.Intent.CategoryDefault, Android.Content.Intent.CategoryBrowsable },
        DataScheme = "myapp")]
public class WebAuthenticationCallbackActivity : WebAuthenticatorCallbackActivity
 {
 }

[dotMorten]

Here’s one implementation that can probably be more or less lifted as is into MAUI: https://github.com/dotMorten/WinUIEx/blob/main/src/WinUIEx/WebAuthenticator.cs You might want to change the use of the module initializer and instead do it on app launch constructor