Ensure that this project has Microsoft.Bcl.Build installed and packages.config is located next to the project file

I received this error while building a UWP app.
Could not locate xxxx\packages.config. Ensure that this project has Microsoft.Bcl.Build installed and packages.config is located next to the project file.
I did check and see the package.config in the right directory and I did have Microsoft.BCL.Build. The only way to get this to work is to close visual studio delete the obj folder in the solutions directory. Once the obj folder is deleted and I reloaded the project in visual studio everything worked again.

Error : DEP1630 : Invalid "TargetOsVersion" property

I was trying to get the Wikipedia sample app for windows store 8 from GitHub to run in visual studio 2015. The app is a HTML app.
https://github.com/wikimedia/apps-win8-wikipedia
When trying to run the app I was getting the following error
DEP1630 : Invalid “TargetOsVersion” property
The solution was to edit the WikipediaMetroTest.jsproj with notepad and change the Visual studio version to 14.0

<VisualStudioVersion>14.0</VisualStudioVersion>

Targeting Mobile only in a windows universal app

To make your UWP app only target windows 10 mobile add the following to your app manifest

<Dependencies>

   <TargetDeviceFamily Name="Windows.Mobile" MinVersion="10.0.x.0" MaxVersionTested="10.0.y.0"/>
</Dependencies>

This MSDN article has more info
https://msdn.microsoft.com/en-us/library/windows/apps/dn986903.aspx