Class not registered when trying to run MAUI App

Question

I am trying to run a MAUI app that was running on a another computer which I cannot access now, but it is not running on my current laptop.

The error I get is before initializing.

System.Runtime.InteropServices.COMException
  HResult=0x80040154
  Message=Class not registered (0x80040154 (REGDB_E_CLASSNOTREG))
  Source=System.Private.CoreLib
  StackTrace:
   at System.Runtime.InteropServices.Marshal.ThrowExceptionForHR(Int32 errorCode)
   at WinRT.ActivationFactory.Get(String typeName)
   at Microsoft.Windows.ApplicationModel.WindowsAppRuntime.DeploymentInitializeOptions.get__objRef_global__Microsoft_Windows_ApplicationModel_WindowsAppRuntime_DeploymentInitializeOptions()
   at Microsoft.Windows.ApplicationModel.WindowsAppRuntime.DeploymentInitializeOptions..ctor()
   at Microsoft.Windows.ApplicationModel.WindowsAppRuntime.DeploymentManagerCS.AutoInitialize.get_Options() in C:\Users\Eneko\.nuget\packages\microsoft.windowsappsdk\1.6.240923002\include\DeploymentManagerAutoInitializer.cs:line 44
   at Microsoft.Windows.ApplicationModel.WindowsAppRuntime.DeploymentManagerCS.AutoInitialize.AccessWindowsAppSDK() in C:\Users\Eneko\.nuget\packages\microsoft.windowsappsdk\1.6.240923002\include\DeploymentManagerAutoInitializer.cs:line 30
   at .cctor()

I tried installing the Windows App SDK x64 version.

Also tried reinstalling the C++ redistributable.

Does anyone know how to solve it?

Answer 1

I ran into a similar issue and managed to fix it by setting the WindowsPackageType in my .csproj file:

<PropertyGroup>
    <!-- ... -->
    <WindowsPackageType>None</WindowsPackageType>
</PropertyGroup>

The WindowsPackageType setting controls how your app is packaged for deployment. When set to None, the app is built as a regular Win32 app (e.g., .exe) without any additional packaging. This is usually enough for debugging in Visual Studio.

It seems that some default settings changed between .NET 8 and .NET 9, which might be the cause of the issue.

P.S. In one of my projects I had additionally modify the commandName parameter in theProperties/launchSettings.json file from MsixPackage to Project

{
  "profiles": {
    "Windows Machine": {
      "commandName": "Project",
      "nativeDebugging": false
    }
  }
}