Element '{http://schemas.microsoft.com/appx/developer/windowsTemplateStudio}Metadata' is unexpected according to content model of parent element '{http://schemas.microsoft.com/appx/manifest/foundation/windows10}Package

Hong 1,051

A UWP app worked fine for a number of years. When I tried to build it today, I got error:

error APPX0501: Validation error. error C00CE014: App manifest validation error: The app manifest must be valid as per schema: Line 57, Column 4, Note: The schema for MaxVersionTested specified does not recognize XML fields with namespace "http://schemas.microsoft.com/appx/developer/windowsTemplateStudio". Please ensure that you have the correct MaxVersionTested specified. Reason: Element '{http://schemas.microsoft.com/appx/developer/windowsTemplateStudio}Metadata' is unexpected according to content model of parent element '{http://schemas.microsoft.com/appx/manifest/foundation/windows10}Package'.

I think the problematic code is the following:

  <Metadata xmlns="http://schemas.microsoft.com/appx/developer/windowsTemplateStudio">
    <Item Name="generator" Value="Windows Template Studio" />
    <Item Name="projectType" Value="Blank" />
    <Item Name="framework" Value="MVVMBasic" />
    <Item Name="platform" Value="Uwp" />
  </Metadata>

It was generated automatically when the project was created.

Could anyone offer a tip on how to fix this?

I wonder if this is related to the recent VS2019 update. I am using VS Version 16.10.1.

Nico Zhu (Shanghai Wicresoft Co,.Ltd.) 12,856 Reputation points

2021-06-23T01:59:21.063+00:00

Derive from error info, it contains error Line number, can you share the that line information?
Nico Zhu (Shanghai Wicresoft Co,.Ltd.) 12,856 Reputation points

2021-06-23T02:02:20.77+00:00

Please try recreate blank app with window template studio. and check if project template works well.
Hong 1,051 Reputation points

2021-06-28T00:24:27.72+00:00

I added xmlns:genTemplate="http://schemas.microsoft.com/appx/developer/windowsTemplateStudio" to the following and modified IgnorableNamespaces accordingly:

Hong 1,051

<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:genTemplate="http://schemas.microsoft.com/appx/developer/windowsTemplateStudio" IgnorableNamespaces="uap mp genTemplate">

Then modified Metadata tag:

  <genTemplate:Metadata xmlns="http://schemas.microsoft.com/appx/developer/windowsTemplateStudio">
    <Item Name="generator" Value="Windows Template Studio" />
    <Item Name="projectType" Value="Blank" />
    <Item Name="framework" Value="MVVMBasic" />
    <Item Name="platform" Value="Uwp" />
  </genTemplate:Metadata>

It is working fine now.
I never manually edited the file before and the app worked fine for a number of years.

Hong 1,051 Reputation points

2021-08-18T14:58:48.87+00:00

Another UWP app has the same problem. The solution also works.