Visual studio - windows 8.1 project error - error APPX1704: The .winmd file 'Windows.winmd'

Question

I'm pretty new in c# programming and i get the above error when i try to run my project this is the full output that i get:

1>D:\Development\kalsefer\trunk\WindowsClient\Source_win_10\Kalsefer\packages\Microsoft.Bcl.Build.1.0.21\build\Microsoft.Bcl.Build.targets(243,5): warning : All projects referencing Kalsefer.Core.csproj must install nuget package Microsoft.Bcl.Build. For more information, see http://go.microsoft.com/fwlink/?LinkID=317569.
1>  Kalsefer.Windows -> D:\Development\kalsefer\trunk\WindowsClient\Source_win_10\Kalsefer\Kalsefer.Windows\bin\x86\DevRelease\Kalsefer.Windows.exe
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): warning APPX1707: No implementation file was provided for the .winmd file 'D:\Development\kalsefer\trunk\WindowsClient\Source_win_10\Kalsefer\Kalsefer.Core\bin\x86\DevRelease\Windows.winmd'. To generate registration information in the app manifest, specify the 'Implementation' metadata on the .winmd reference item in the project file.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): error APPX1704: The .winmd file 'Windows.winmd' contains type 'Windows.Storage.ISetVersionRequest'. The use of the Windows namespace is reserved.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): error APPX1704: The .winmd file 'Windows.winmd' contains type 'Windows.Storage.StreamedFileDataRequest'. The use of the Windows namespace is reserved.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): error APPX1704: The .winmd file 'Windows.winmd' contains type 'Windows.Storage.IStorageItemProperties2'. The use of the Windows namespace is reserved.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): error APPX1704: The .winmd file 'Windows.winmd' contains type 'Windows.Storage.StorageDeleteOption'. The use of the Windows namespace is reserved.
1>C:\Program Files (x86)\MSBuild\Microsoft\VisualStudio\v14.0\AppxPackage\Microsoft.AppXPackage.Targets(1930,5): error APPX1704: The .winmd file 'Windows.winmd' contains type 'Windows.Storage.FileAccessMode'. The use of the Windows namespace is reserved.

and don't write the all errors because i have 4000 more lines with the same error but in different files. I'm stick on on this error two days and i'll be happy to get any help.

Answer 1

I solved my issue and the problem was that i add "using" for ui element and the visual studio is automatically add reference to "Window" that makes all the 4000 errors, i remove this reference and everything was solved.