"Validation failed. Error C00CE014: Application manifest validation failed" when trying to create Windows Store app packages

I have been struggling with this error for several hours. I can build and deploy the app without problem, it just won't create distribution packages (Project> Store> Create App Packages)

The problem is rather strange. Here is my Package.appxmanifest file:

<?xml version="1.0" encoding="utf-8"?>
<Package xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10" xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest" xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10" xmlns:uap3="http://schemas.microsoft.com/appx/manifest/uap/windows10/3" IgnorableNamespaces="uap mp uap3">
  <Identity Name="481f1dca-fa19-4642-8e95-9208a4c9265f" Publisher="CN=mrrey" Version="1.1.8.0" />
  <mp:PhoneIdentity PhoneProductId="06509575-8d8e-4beb-aa84-4ea390365781" PhonePublisherId="06509575-8d8e-4beb-aa84-4ea390365785" />
  <Properties>
    <DisplayName>XYZ MusicBox</DisplayName>
    <PublisherDisplayName>mrrey</PublisherDisplayName>
    <Logo>Assets\StoreLogo.png</Logo>
  </Properties>
  <Dependencies>
    <TargetDeviceFamily Name="Windows.Universal" MinVersion="10.0.0.0" MaxVersionTested="10.0.0.0" />
  </Dependencies>
  <Resources>
    <Resource Language="x-generate" />
  </Resources>
  <Applications>
    <Application Id="App" Executable="$targetnametoken$.exe" EntryPoint="XYZ_MusicBox.App">
      <uap:VisualElements DisplayName="XYZ MusicBox" Square150x150Logo="Assets\Square150x150Logo.png" Square44x44Logo="Assets\Square44x44Logo.png" Description="XYZ MusicBox" BackgroundColor="transparent">
        <uap:DefaultTile Wide310x150Logo="Assets\Wide310x150Logo.png">
        </uap:DefaultTile>
        <uap:SplashScreen Image="Assets\SplashScreen.png" />
      </uap:VisualElements>
    </Application>
  </Applications>
  <Capabilities>
    <Capability Name="internetClient" />
    <uap:Capability Name="musicLibrary" />
    <uap3:Capability Name="backgroundMediaPlayback" />
    <DeviceCapability Name="microphone" />
  </Capabilities>
</Package>

      

        
        
        
      

    

This is the initial state of my manifest. After I click Create

in the wizard, it will start creating packages. Output:

...
1>     1018 ms  Csc                                        2 calls
1>     1091 ms  ResolveAssemblyReference                   1 calls
1>     3498 ms  CompileXaml                                2 calls
1>     3615 ms  GenerateAppxManifest                       1 calls
1>
1>Build FAILED.
1>
1>Time Elapsed 00:00:11.30
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
========== Package: 0 succeeded, 1 failed ===========
========== App Bundle: 0 succeeded, 1 failed ===========

      

        
        
        
      

    

After that, when I try to open the file Package.appxmanifest

, the developer doesn't want to load due to a compiler error:

Severity    Code    Description Project File    Line    Suppression State
Error       Validation error. error C00CE014: App manifest validation error: The app manifest must be valid as per schema: Line 34, Column 6, Reason: Element 'Capability' is unexpected according to content model of parent element '{http://schemas.microsoft.com/appx/manifest/foundation/windows10}Capabilities'. Expecting: {http://schemas.microsoft.com/appx/manifest/foundation/windows10}CapabilityChoice, {http://schemas.microsoft.com/appx/manifest/foundation/windows10}DeviceCapability. XYZ MusicBox    C:\Users\mrrey\Box Sync\XYZ MusicBox\XYZ MusicBox\bin\x86\Debug\AppxManifest.xml        

      

        
        
        
      

    

The weirdest part of it all is the fact that when building the package, VS modifies my original file appxmanifest

and adds this line to the capabilities:

<Capability Name="backgroundMediaPlayback" xmlns="" />

      

        
        
        
      

    

As you can see in the above code, I have already added this capability, but it is required to use the namespace correctly uap3:

. For some reason, he still forces it. What about this null xmlns attribute?

After trying to create packages, I also get a few warnings like this:

Severity    Code    Description Project File    Line    Suppression State
Warning     Imported schema for namespace 'http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities/3' was not resolved.  XYZ MusicBox    C:\Users\mrrey\Box Sync\XYZ MusicBox\XYZ MusicBox\Package.appxmanifest  17  

      

        
        
        
      

    

Everything works correctly when I remove the original opportunity Background Media Playback

, but this is not something I can afford as this is a media player app. Obviously there is something wrong with this settings / projects configuration, but I cannot find it.

This doesn't happen when I just build the solution and deploy the application to Local Machine

/ Device

/ Emulators.

I am using modern Visual Studio 2017 and Windows 10 (version 10.0.14393 Build 14393).

Has anyone faced a similar problem? Am I doing something wrong or is this a bug?

Thank!

Edit: to make even more clear: these short warning (Imported scheme for the namespace ...) are obscene <Applications>

, <Application>

, <Properties>

and <Dependencies>

.

Edit2: I don't even want to think about it . Somehow I broke it even more.