title: Xamarin.Forms new project creation has countless errors. Something wrong with nuget?
body: <p>I am new to Visual Studio.</p>
  
  <p>creating a new project with Xamarin.Forms template gives countless errors, such as</p>
  
  <blockquote>
    <p>"Can not resolve reference: <code>Xamarin.Forms.Xaml</code>, referenced by
    <code>App4</code>. Please add a NuGet package or assembly reference for
    <code>Xamarin.Forms.Xaml</code>, or remove the reference to <code>App4</code>.  App4.Android"
    "the referenced component "system.xml" could not be found." "the
    reference component "system" could not be found."</p>
  </blockquote>
  
  <p>I think something substantial is wrong with the installation; I have tried uninstalling, repairing, and tried VS 2017 and VS 2019. Nothing seems to work.</p>
  
  <p>I tried to manually install the nuget packages, from the package manager and the console. The package manager indicates all the packages are uptodate, and does not let me install any new packages; from the console, installing any package results in this error:</p>
  
  <blockquote>
    <p>"Install-Package Xamarin.Forms -Version 3.6.0.344457 Restoring
    packages for
    C:\Users\Navid\source\repos\App4\App4\App4.Android\App4.Android.csproj...
    GET
    <a href="https://www.nuget.org/packages/FindPackagesById()?id=" rel="nofollow noreferrer">https://www.nuget.org/packages/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0
    GET
    <a href="https://nuget.org/FindPackagesById()?id=" rel="nofollow noreferrer">https://nuget.org/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0
    NotFound
    <a href="https://nuget.org/FindPackagesById()?id=" rel="nofollow noreferrer">https://nuget.org/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0
    121ms Retrying 'FindPackagesByIdAsyncCore' for source
    '<a href="https://nuget.org/FindPackagesById()?id=" rel="nofollow noreferrer">https://nuget.org/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0'.
    Response status code does not indicate success: 404 (Not Found).   GET
    <a href="https://nuget.org/FindPackagesById()?id=" rel="nofollow noreferrer">https://nuget.org/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0
    NotFound
    <a href="https://www.nuget.org/packages/FindPackagesById()?id=" rel="nofollow noreferrer">https://www.nuget.org/packages/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0
    168ms Install-Package : Failed to retrieve information about
    'System.Numerics.Vectors' from remote source
    '<a href="https://nuget.org/FindPackagesById()?id=" rel="nofollow noreferrer">https://nuget.org/FindPackagesById()?id=</a>'System.Numerics.Vectors'&amp;semVerLevel=2.0.0'.
    Response status code does not indicate success: 404 (Not Found). At
    line:1 char:1
    + Install-Package Xamarin.Forms -Version 3.6.0.344457
    + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        + CategoryInfo          : NotSpecified: (:) [Install-Package], Exception
        + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PackageManagement.PowerShellCmdlets.InstallPackageCommand
    Time Elapsed: 00:00:01.0871186"</p>
  </blockquote>