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NuGet Pack error: The default XML namespace of the project must be the MSBuild XML namespace

I am following the MS Instructions for preparing a NuGet Package on a .NET 4.7 Class Library I created with VS 2022. Unlike the .NET 6 Library, there are no project properties that facilitate building a NuGet package.
When I run the command nuget pack I get this error. Of course, if I look at the CSPROJ file, the namespace is on the Project element, so the error is not helpful.
Now, this differs from the other Q&A I found on StackExchange, because it occurs on the nuget pack command, so the other questions don't answer this one.
Does anyone know how to resolve this?
The CSPROJ file is here:
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
<PropertyGroup>
<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
<ProjectGuid>{6A38AC27-E82D-47CF-B1C6-D987D7BCAE0C}</ProjectGuid>
<OutputType>Library</OutputType>
<AppDesignerFolder>Properties</AppDesignerFolder>
<RootNamespace>CodaRESTClient.NET</RootNamespace>
<AssemblyName>CodaRESTClient.NET</AssemblyName>
<TargetFrameworkVersion>v4.7.2</TargetFrameworkVersion>
<FileAlignment>512</FileAlignment>
<Deterministic>true</Deterministic>
<NuGetPackageImportStamp>
</NuGetPackageImportStamp>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>bin\Debug\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
<DebugType>pdbonly</DebugType>
<Optimize>true</Optimize>
<OutputPath>bin\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<PropertyGroup>
<ApplicationIcon>Coda Logo - Image only.ico</ApplicationIcon>
</PropertyGroup>
<ItemGroup>
<Reference Include="Microsoft.Bcl.AsyncInterfaces, Version=6.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\Microsoft.Bcl.AsyncInterfaces.6.0.0\lib\net461\Microsoft.Bcl.AsyncInterfaces.dll</HintPath>
</Reference>
<Reference Include="Newtonsoft.Json, Version=13.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
<HintPath>..\packages\Newtonsoft.Json.13.0.1\lib\net45\Newtonsoft.Json.dll</HintPath>
</Reference>
<Reference Include="RestSharp, Version=108.0.1.0, Culture=neutral, PublicKeyToken=598062e77f915f75, processorArchitecture=MSIL">
<HintPath>..\packages\RestSharp.108.0.1\lib\netstandard2.0\RestSharp.dll</HintPath>
</Reference>
<Reference Include="System" />
<Reference Include="System.Buffers, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Buffers.4.5.1\lib\net461\System.Buffers.dll</HintPath>
</Reference>
<Reference Include="System.Core" />
<Reference Include="System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Memory.4.5.4\lib\net461\System.Memory.dll</HintPath>
</Reference>
<Reference Include="System.Numerics" />
<Reference Include="System.Numerics.Vectors, Version=4.1.4.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Numerics.Vectors.4.5.0\lib\net46\System.Numerics.Vectors.dll</HintPath>
</Reference>
<Reference Include="System.Runtime.CompilerServices.Unsafe, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL">
<HintPath>..\packages\System.Runtime.CompilerServices.Unsafe.6.0.0\lib\net461\System.Runtime.CompilerServices.Unsafe.dll</HintPath>
</Reference>
<Reference Include="System.Text.Encodings.Web, Version=6.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Text.Encodings.Web.6.0.0\lib\net461\System.Text.Encodings.Web.dll</HintPath>
</Reference>
<Reference Include="System.Text.Json, Version=6.0.0.6, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Text.Json.6.0.6\lib\net461\System.Text.Json.dll</HintPath>
</Reference>
<Reference Include="System.Threading.Tasks.Extensions, Version=4.2.0.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.Threading.Tasks.Extensions.4.5.4\lib\net461\System.Threading.Tasks.Extensions.dll</HintPath>
</Reference>
<Reference Include="System.ValueTuple, Version=4.0.3.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51, processorArchitecture=MSIL">
<HintPath>..\packages\System.ValueTuple.4.5.0\lib\net47\System.ValueTuple.dll</HintPath>
</Reference>
<Reference Include="System.Web" />
<Reference Include="System.Xml.Linq" />
<Reference Include="System.Data.DataSetExtensions" />
<Reference Include="Microsoft.CSharp" />
<Reference Include="System.Data" />
<Reference Include="System.Net.Http" />
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="Client.cs" />
<Compile Include="Client_Comment.cs" />
<Compile Include="Client_Discussion.cs" />
<Compile Include="Client_Errors.cs" />
<Compile Include="Client_Moderator.cs" />
<Compile Include="Client_Subscriptions.cs" />
<Compile Include="Client_Troubleshoot.cs" />
<Compile Include="Client_Vote.cs" />
<Compile Include="Properties\AssemblyInfo.cs" />
<Compile Include="SerializableDictionary.cs" />
</ItemGroup>
<ItemGroup>
<None Include="app.config" />
<None Include="packages.config" />
</ItemGroup>
<ItemGroup>
<Content Include="Coda Logo - Image only.ico" />
</ItemGroup>
<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
<Import Project="..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets" Condition="Exists('..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets')" />
<Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
<PropertyGroup>
<ErrorText>This project references NuGet package(s) that are missing on this computer. Use NuGet Package Restore to download them. For more information, see http://go.microsoft.com/fwlink/?LinkID=322105. The missing file is {0}.</ErrorText>
</PropertyGroup>
<Error Condition="!Exists('..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets')" Text="$([System.String]::Format('$(ErrorText)', '..\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets'))" />
</Target>
</Project>
... and the NUSPEC file:
<?xml version="1.0"?>
<package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
<metadata>
<id>$id$</id>
<version>$version$</version>
<title>$title$</title>
<authors>$author$</authors>
<owners>$author$</owners>
<licenseUrl>https://licenses.nuget.org/CATOSL-1.1</licenseUrl>
<projectUrl>https://github.com/info-tpr/CodaEA</projectUrl>
<iconUrl>https://www.codaea.io/images/CodaEA.png</iconUrl>
<requireLicenseAcceptance>false</requireLicenseAcceptance>
<description>$description$</description>
<releaseNotes>Summary of changes made in this release of the package.</releaseNotes>
<copyright>Copyright 2022, The Parallel Revolution LLC, All Rights Reserved</copyright>
<tags>error code analysis</tags>
</metadata>
</package>
The full error message from nuget command is:
nuget : The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add
xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the <Project> element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format.
E:\Data\dotNetDev\codaea\CodaRESTServer\packages\System.Text.Json.6.0.6\build\System.Text.Json.targets
At line:1 char:1
+ nuget pack
+ ~~~~~~~~~~
+ CategoryInfo : NotSpecified: (The default XML...xt.Json.targets:String) [], RemoteException
+ FullyQualifiedErrorId : NativeCommandError

C# MSBuild not including the NuGet packages (works in Visual Studio 17)

I am using PackageReference in my .csproj file and my build works in Visual Studio (2017). I'm building with .net 4.5 I have looked at this:
(MSBuild not adding a /reference for nuget PackageReference when building with jenkins)
I was at first having the issue on our build server so I tried it locally on my computer. I do a restore and then the build (or rebuild). the error is:
(CoreCompile target) ->
Properties\AssemblyInfo.cs(25,12): error CS0246: The type or namespace name 'log4net' could not be found (are you missing a using directive or an assembly reference?)
And in my project I have
<ItemGroup>
<PackageReference Include="log4net">
<Version>2.0.12</Version>
</PackageReference>
Thanks in advance.
Update
I created a simple solution/project that just includes one Nuget Package. I also created it with the latest framework in case that had any bearing on the issue. Again, it builds in VS2017 but fails using MSBuild the .csproj file is
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
<PropertyGroup>
<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
<ProjectGuid>{9A64612A-63A2-4CA5-8470-75DD978D7449}</ProjectGuid>
<OutputType>Exe</OutputType>
<RootNamespace>testNetwonNugetProject</RootNamespace>
<AssemblyName>testNetwonNugetProject</AssemblyName>
<TargetFrameworkVersion>v4.8</TargetFrameworkVersion>
<FileAlignment>512</FileAlignment>
<AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
<Deterministic>true</Deterministic>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<PlatformTarget>AnyCPU</PlatformTarget>
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>bin\Debug\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
<PlatformTarget>AnyCPU</PlatformTarget>
<DebugType>pdbonly</DebugType>
<Optimize>true</Optimize>
<OutputPath>bin\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<ItemGroup>
<Reference Include="System" />
<Reference Include="System.Core" />
<Reference Include="System.Xml.Linq" />
<Reference Include="System.Data.DataSetExtensions" />
<Reference Include="Microsoft.CSharp" />
<Reference Include="System.Data" />
<Reference Include="System.Net.Http" />
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="Program.cs" />
<Compile Include="Properties\AssemblyInfo.cs" />
</ItemGroup>
<ItemGroup>
<None Include="App.config" />
</ItemGroup>
<ItemGroup>
<PackageReference Include="Newtonsoft.Json">
<Version>13.0.1</Version>
</PackageReference>
</ItemGroup>
<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>
I verified that on restore the files are added to the project obj folder as well as user/roaming/nuget and user/.nuget/packages. I get the same error message as above.

Embed Nuget dependencies in another nuget with PrivateAssets

I have a netstandard2.0 nugget package that has some dependencies:
<!-- Nugget Package dependencies -->
<ItemGroup>
<PackageReference Include="JetBrains.Annotations" Version="2020.1.0" PrivateAssets="All" />
<PackageReference Include="Serilog" Version="2.9.0" PrivateAssets="All" />
<PackageReference Include="Newtonsoft.Json" Version="12.0.3" PrivateAssets="All" />
<PackageReference Include="Newtonsoft.Json.Schema" Version="3.0.13" PrivateAssets="All" />
<PackageReference Include="Serilog.Enrichers.Thread" Version="3.1.0" PrivateAssets="All" />
<PackageReference Include="Serilog.Sinks.Async" Version="1.4.0" PrivateAssets="All" />
<PackageReference Include="Serilog.Sinks.Console" Version="3.1.1" PrivateAssets="All" />
<PackageReference Include="Serilog.Sinks.File" Version="4.1.0" PrivateAssets="All" />
</ItemGroup>
Every time I install this package on a another project, it adds it's dependencies, like:
<ItemGroup>
<Reference Include="PackageXPTO, Version=0.0.0.0, Culture=neutral, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\PackageXPTO.dll</HintPath>
</Reference>
<Reference Include="JetBrains.Annotations, Version=2020.1.0.0, Culture=neutral, PublicKeyToken=1010a0d8d6380325, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\JetBrains.Annotations.dll</HintPath>
</Reference>
<Reference Include="Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\Newtonsoft.Json.dll</HintPath>
</Reference>
<Reference Include="Newtonsoft.Json.Schema, Version=3.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\Newtonsoft.Json.Schema.dll</HintPath>
</Reference>
<Reference Include="Serilog, Version=2.0.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\Serilog.dll</HintPath>
</Reference>
<Reference Include="Serilog.Enrichers.Thread, Version=2.0.0.0, Culture=neutral, PublicKeyToken=24c2f752a8e58a10, processorArchitecture=MSIL">
<HintPath>..\packages\PackageXPTO.1.1.0\lib\netstandard2.0\Serilog.Enrichers.Thread.dll</HintPath>
</Reference>
(...)
This is messing with a project that I have that already depends on Newtonsoft.Json: the old dependency will now be related to the nugget and not a direct dependency: so, on the future, if this nugget no longer deppends on the Newtonsoft.Json, the dependency will be removed, but the project actually needs it.
Package configurations:
<PropertyGroup>
<AssemblyName>PackageXPTO</AssemblyName>
<RootNamespace>PackageXPTO</RootNamespace>
<TargetFramework>netstandard2.0</TargetFramework>
<Version>1.1.0</Version>
<SignAssembly>true</SignAssembly>
<AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
<AppxAutoIncrementPackageRevision>true</AppxAutoIncrementPackageRevision>
<CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
<GenerateAssemblyInfo>true</GenerateAssemblyInfo>
<LangVersion>7.2</LangVersion>
<PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
<GeneratePackageOnBuild>true</GeneratePackageOnBuild>
<GenerateDocumentationFile>true</GenerateDocumentationFile>
<GenerateAssemblyVersionAttribute>false</GenerateAssemblyVersionAttribute>
<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
<TreatSpecificWarningsAsErrors />
<PublishRepositoryUrl>true</PublishRepositoryUrl>
<EmbedUntrackedSources>true</EmbedUntrackedSources>
<IncludeSymbols>true</IncludeSymbols>
<SymbolPackageFormat>snupkg</SymbolPackageFormat>
<TargetsForTfmSpecificBuildOutput>IncludeDependentDlls</TargetsForTfmSpecificBuildOutput>
</PropertyGroup>
Already tried to merge built .dll files, but didn't work
<!-- Auto bundler - used to apply package reference dll files -->
<!-- Include all .dll files under build directory, excluding the self one (to avoid errors) -->
<Target Name="IncludeDependentDlls" DependsOnTargets="ResolveReferences">
<ItemGroup>
<BuildOutputInPackage Include="$(OutputPath)\*.dll" Exclude="$(OutputPath)\$(AssemblyName).dll" />
</ItemGroup>
</Target>

No references were found in the windows sdk (Windows 1903)

I want to create simple toast notification to action center in windows 10 from a WPF app using this article.
But I got problem on Step 2:
Right click on the project => Add => Reference... => Windows => Core
What I checked:
Windows 10 SDK Installation:
Same issue with a WPF project
And this is my csproj file:
<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
<PropertyGroup>
<Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
<Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
<ProjectGuid>{A5A389ED-4BBB-4EF4-A8A4-45DD3D0AF9AE}</ProjectGuid>
<OutputType>WinExe</OutputType>
<RootNamespace>WpfApp3</RootNamespace>
<AssemblyName>WpfApp3</AssemblyName>
<TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
<TargetPlatformVersion>10.0.10240.0</TargetPlatformVersion>
<FileAlignment>512</FileAlignment>
<ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
<WarningLevel>4</WarningLevel>
<AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
<Deterministic>true</Deterministic>
<TargetFrameworkProfile />
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<PlatformTarget>AnyCPU</PlatformTarget>
<DebugSymbols>true</DebugSymbols>
<DebugType>full</DebugType>
<Optimize>false</Optimize>
<OutputPath>bin\Debug\</OutputPath>
<DefineConstants>DEBUG;TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
<PlatformTarget>AnyCPU</PlatformTarget>
<DebugType>pdbonly</DebugType>
<Optimize>true</Optimize>
<OutputPath>bin\Release\</OutputPath>
<DefineConstants>TRACE</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
</PropertyGroup>
<ItemGroup>
<Reference Include="System" />
<Reference Include="System.Data" />
<Reference Include="System.Xml" />
<Reference Include="Microsoft.CSharp" />
<Reference Include="System.Core" />
<Reference Include="System.Xml.Linq" />
<Reference Include="System.Data.DataSetExtensions" />
<Reference Include="System.Net.Http" />
<Reference Include="System.Xaml">
<RequiredTargetFramework>4.0</RequiredTargetFramework>
</Reference>
<Reference Include="WindowsBase" />
<Reference Include="PresentationCore" />
<Reference Include="PresentationFramework" />
</ItemGroup>
<ItemGroup>
<ApplicationDefinition Include="App.xaml">
<Generator>MSBuild:Compile</Generator>
<SubType>Designer</SubType>
</ApplicationDefinition>
<Page Include="MainWindow.xaml">
<Generator>MSBuild:Compile</Generator>
<SubType>Designer</SubType>
</Page>
<Compile Include="App.xaml.cs">
<DependentUpon>App.xaml</DependentUpon>
<SubType>Code</SubType>
</Compile>
<Compile Include="MainWindow.xaml.cs">
<DependentUpon>MainWindow.xaml</DependentUpon>
<SubType>Code</SubType>
</Compile>
</ItemGroup>
<ItemGroup>
<Compile Include="Properties\AssemblyInfo.cs">
<SubType>Code</SubType>
</Compile>
<Compile Include="Properties\Resources.Designer.cs">
<AutoGen>True</AutoGen>
<DesignTime>True</DesignTime>
<DependentUpon>Resources.resx</DependentUpon>
</Compile>
<Compile Include="Properties\Settings.Designer.cs">
<AutoGen>True</AutoGen>
<DependentUpon>Settings.settings</DependentUpon>
<DesignTimeSharedInput>True</DesignTimeSharedInput>
</Compile>
<EmbeddedResource Include="Properties\Resources.resx">
<Generator>ResXFileCodeGenerator</Generator>
<LastGenOutput>Resources.Designer.cs</LastGenOutput>
</EmbeddedResource>
<None Include="Properties\Settings.settings">
<Generator>SettingsSingleFileGenerator</Generator>
<LastGenOutput>Settings.Designer.cs</LastGenOutput>
</None>
</ItemGroup>
<ItemGroup>
<None Include="App.config" />
</ItemGroup>
<Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
</Project>
This error occurs after the update to Windows 1903, because Visual studio can not access C:\Windows\System32\WinMetadata

On updating to the May 2019 release of Windows 10 the directory C:\WINDOWS\SysWOW64\WinMetadata is removed and this is where Visual Studio is 2017 and 2019 is looking for all of the files.
There is 2 way to solve this:
1. Click Browse in reference manager and chose your reference from C:\WINDOWS\System32\WinMetadata.
2. Copy WinMetadata folder from C:\WINDOWS\System32\WinMetadata to C:\WINDOWS\SysWOW64\WinMetadata. and then re-open reference manager.

Looks like the parent bug is documented at https://developercommunity.visualstudio.com/content/problem/446490/visual-studio-cant-see-winmetadatadirectory-in-cwi.html
For me I clicked browse and used this path %windir%\Sysnative\WinMetadata and it worked for me. Windows 10 1903 \ VS 17

I've reproduced your issue. The node <TargetPlatformVersion> should be below the existing node <TargetFrameworkVersion> node.
<TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
<TargetPlatformVersion>10.0.10240.0</TargetPlatformVersion>
But there is the separate PropertyGroup with this node in your project file.

Visual Studio can not access the C:\Windows\System32\WinMetadata directory to load the windows SDK on Windows 1903.
So a downgrade from windows 1903 to 1803 solved this issue.
I have reported this problem on the visual studio developer community page.

Windows 1903:
Copy WinMetadata folder from (hidden folder) C:\WINDOWS\sysnative\WinMetadata to C:\WINDOWS\SysWOW64\WinMetadata.
Re-open reference manager.

​The folder %windir%\Sysnative\WinMetadata does not seem to exist on my Windows 1903 (OS Build 18362.900).
My workaround was to make a local copy of the required files in %windir%\System32\WinMetadata (e.g. under a lib folder in your solution) and reference them from there.
In my case, this is how I got a hold of the Windows.Data.winmd and Windows.UI.winmd files (couldn't find them on NuGet).

How can I specify exact output path for new .csproj file format? [duplicate]

This question already has answers here:
How do I set `OutputPath` in a Visual Studio 2017 project (new .csproj file format) without the target framework cluttering the resolved path?
(2 answers)
Closed 5 years ago.
I'm playing around with using the new .csproj file format.
I want my project to build to:
C:\Development\Source\DotNet\bin\x64\Debug\
But it seems to be implicitly adding to the path and building it at:
C:\Development\Source\DotNet\bin\x64\Debug\net46
Is there a way to prevent it from doing that?
My project is:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net46</TargetFramework>
<Platforms>x64</Platforms>
<ApplicationIcon />
<OutputType>Exe</OutputType>
<StartupObject />
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
<OutputPath>C:\Development\Source\DotNet\bin\x64\Debug\</OutputPath>
</PropertyGroup>
<ItemGroup>
<Reference Include="AssetManagement_Gen">
<HintPath>..\..\Development\Source\DotNet\bin\x64\Debug\AssetManagement_Gen.dll</HintPath>
</Reference>
<Reference Include="EXPLink">
<HintPath>..\..\Development\Source\DotNet\bin\x64\Debug\EXPLink.dll</HintPath>
</Reference>
<Reference Include="IvaraCommon">
<HintPath>..\..\Development\Source\DotNet\bin\x64\Debug\IvaraCommon.dll</HintPath>
</Reference>
<Reference Include="NLog">
<HintPath>..\..\Development\Source\DotNet\bin\x64\Debug\NLog.dll</HintPath>
</Reference>
<Reference Include="System.Windows.Forms" />
</ItemGroup>
</Project>
If I open it in visual studio it also shows up with the "net46" appended to the output path.
For my posterity, the combination of <OutputPath> and <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath> lets you get a completely custom path.
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>net46</TargetFramework>
<AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
<Platforms>x64</Platforms>
<ApplicationIcon />
<OutputType>Exe</OutputType>
<StartupObject />
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
<OutputPath>..\..\..\bin\$(Platform)\$(Configuration)</OutputPath>
</PropertyGroup>
<PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
<OutputPath>..\..\..\bin\$(Platform)\$(Configuration)</OutputPath>
</PropertyGroup>
<ItemGroup>
<Reference Include="AssetManagement_Gen">
<HintPath>$(OutDir)\AssetManagement_Gen.dll</HintPath>
</Reference>
<Reference Include="EXPLink">
<HintPath>$(OutDir)\EXPLink.dll</HintPath>
</Reference>
<Reference Include="IvaraCommon">
<HintPath>$(OutDir)\IvaraCommon.dll</HintPath>
</Reference>
<Reference Include="NLog">
<HintPath>$(OutDir)\NLog.dll</HintPath>
</Reference>
<Reference Include="System.Windows.Forms" />
</ItemGroup>
</Project>

I found the following post:
https://compiledexperience.com/blog/posts/multi-targeting-output-path
If you want to disable this automatic appending, for instance you’re only going to be using one target framework or you’re defining a different output path per framework then you can use AppendTargetFrameworkToOutputPath.
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard1.4</TargetFramework>
<AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
</PropertyGroup>
</Project>