title: MSB3073: The command dotnet bundle clean exited with code 1 in a Visual Studio 2019 Asp.NetCore project
body: <p>I got the error <code>MSB3073: The command dotnet bundle clean exited with code 1</code> in a Visual Studio 2019 Asp.NetCore project. This issue only occured after I updated my Visual Studio yesterday.</p>
  
  <pre class="lang-sh prettyprint-override"><code>&gt; dotnet bundle clean
  
  NuGet.Packaging.Core.PackagingException: Der Fallbackpaketordner "C:\ProgramData\Xamarin\NuGet" wurde nicht gefunden.
     at NuGet.Packaging.FallbackPackagePathResolver..ctor(String userPackageFolder, IEnumerable`1 fallbackPackageFolders)
     at Microsoft.DotNet.Cli.Utils.LockFileExtensions.GetPackageDirectory(LockFile lockFile, LockFileTargetLibrary library)
     at Microsoft.DotNet.Cli.Utils.PackagedCommandSpecFactory.GetCommandFilePath(LockFile lockFile, LockFileTargetLibrary toolLibrary, LockFileItem runtimeAssembly)
     at Microsoft.DotNet.Cli.Utils.PackagedCommandSpecFactory.CreateCommandSpecFromLibrary(LockFileTargetLibrary toolLibrary, String commandName, IEnumerable`1 commandArguments, IEnumerable`1 allowedExtensions, LockFile lockFile, CommandResolutionStrategy commandResolutionStrategy, String depsFilePath, String runtimeConfigPath)
     at Microsoft.DotNet.Cli.Utils.ProjectToolsCommandResolver.ResolveCommandSpecFromToolLibrary(SingleProjectInfo toolLibraryRange, String commandName, IEnumerable`1 args, IProject project)
     at Microsoft.DotNet.Cli.Utils.ProjectToolsCommandResolver.ResolveCommandSpecFromAllToolLibraries(IEnumerable`1 toolsLibraries, String commandName, IEnumerable`1 args, IProject project)
     at Microsoft.DotNet.Cli.Utils.ProjectToolsCommandResolver.ResolveFromProjectTools(CommandResolverArguments commandResolverArguments)
     at Microsoft.DotNet.Cli.Utils.ProjectToolsCommandResolver.Resolve(CommandResolverArguments commandResolverArguments)
     at Microsoft.DotNet.Cli.Utils.CompositeCommandResolver.Resolve(CommandResolverArguments commandResolverArguments)
     at Microsoft.DotNet.Cli.Utils.CommandResolver.TryResolveCommandSpec(ICommandResolverPolicy commandResolverPolicy, String commandName, IEnumerable`1 args, NuGetFramework framework, String configuration, String outputPath, String applicationName)
     at Microsoft.DotNet.Cli.Utils.Command.Create(ICommandResolverPolicy commandResolverPolicy, String commandName, IEnumerable`1 args, NuGetFramework framework, String configuration, String outputPath, String applicationName)
     at Microsoft.DotNet.Cli.Utils.Command.Create(String commandName, IEnumerable`1 args, NuGetFramework framework, String configuration, String outputPath, String applicationName)
     at Microsoft.DotNet.Cli.Program.ProcessArgs(String[] args, ITelemetry telemetryClient)
     at Microsoft.DotNet.Cli.Program.Main(String[] args)
  </code></pre>
  
  <p>The Visual Studio version is 16.1.0.</p>
  
  <p>I don't know why dotnet uses the fallback folder. Neither do I know why the folder isn't there because I have installed Xamarin support in Visual Studio 2019.</p>