Error 0x80073B0C while executing the Windows App Certification Kit for a Windows 10 app

I have an existing Windows 8.1 Universal App and I added a new Windows 10 Universal Windows App to the existing solution.

I migrated the UI and can now successfully launch my ported Windows 10 app. However while launching the Windows App Certification Kit for to create an app package I get the following error (unfortunately in German):

Fehler "0x80073CF6" beim AppX Deployment-Vorgang für Paket "PublisherId.StopNow_5.0.0.0_neutral_~_magicstring". Der Fehlertext lautet: C:\Program Files\WindowsApps\<PackageId>\AppxManifest.xml(22,62): Fehler 0x80073B0C: Das Paket "projectname_5.0.0.0_x64__magicstring" kann aufgrund des folgenden Fehlers beim Bestimmen, ob die Dateiressource "Assets\Square150x150Logo.png" lokalisiert werden kann, nicht registriert werden: ResourceMap oder NamedResource beinhaltet ein Element, das keine standardmäßige oder neutrale Ressource besitzt. . Überprüfen Sie, ob die Dateiressource definiert ist und ob mindestens eine Instanz in der Datei "resources.pri" definiert ist, die in diesem Paket enthalten ist.

The message says, that it cannot be determined whether given file resource can be localized. I should check whether the file exists and I should check whether a file is defined in resources.pri.

Based on this message I can say that the file Square150x150Logo.png does not exist, only a file Square150x150Logo.scale-100.png which I guess should be okay.

About the second part of the message: I can't find a resources.pri.

Update

I removed the file in question (Square150x150Logo.scale-100.png) just to see what happens. Now I get the same error for Splashscreen.png. Looks like a more general problem with my assets.

I have to add, that the app runs fine from the debugger and Visual Studio shows no errors in the Package.appxmanifest editor.

After I created the project, I removed all default assets from the project and added my own ones. Maybe something went wrong there.

I still have now idea what was the problem but here is how I fixed it:

I rolled back all my changes to the assets and edited my own graphics into the default assets created by the project wizard.

That fixed the problem for me. So all I can say is, that the problem was really related to the different tile / splashcreen resources.