First I get error that I must Deploy the application. I have Deploy check box checked in Configuration Manager but have worked around this by choosing the Project in solution explorer, right click and choose Deploy from menu.

I still get error: DEP0700: Registration of the app failed. [0x80073CF6] AppxManifest.xml(42,10): error 0x80080204: Cannot register the PlcWorkOrderUwp-Deploy-Package_2.1.18.0_x64__pemvxjdcr8wxc package because the extension is missing an EntryPoint or StartPage attribute. PlcWorkOrderUwp

I have run out of articles to review for an answer. I am providing a picture of the pieces I believe could be part of the problem. Based on my reading I have everything in place so not sure what to try next.

I removed the /bin and /obj folders. I reviewed the App.g.is.cs generated code. This was a UWP app with a Package project and I moved the Package Manifest and Images to the WinUI project and removed the Packaging project to make it a single project WinUI 3 packaged project.

I am running from my local drive, there is no encryption, the Package Manifest is in the project. I did not choose a project template of Packaged Project but used the Upgrade Assistant to convert my UWP application. https://learn.microsoft.com/en-us/windows/apps/windows-app-sdk/migrate-to-windows-app-sdk/upgrade-assistant

Another caveat of the UWP project was separate projects to use the Excel and Outlook interop that I could not use from the UWP application. I have removed these projects but it appears some remnants may still be in the Package Manifest .XML file under Extensions not sure why these are still being created with the projects removed from the WinUI 3 application.

<desktop:Extension Category=”windows.fullTrustProcess” Executable=”LauncherLauncher.exe”>
desktop:FullTrustProcess
<desktop:ParameterGroup GroupId=”Excel” Parameters=”/excel” />
<desktop:ParameterGroup GroupId=”Outlook” Parameters=”/outlook” />
</desktop:FullTrustProcess>
</desktop:Extension>
<uap:Extension Category=”windows.appService”>
<uap:AppService Name=”ExcelInteropService” />
</uap:Extension>
<uap:Extension Category=”windows.appService”>
<uap:AppService Name=”OutlookInteropService” />
</uap:Extension>