Build for Windows with appx=UAP fails with Microsoft.NuGet.targets error

Project working with windows@4.1.0 now updated to 4.2.0 gives the following error during building:

...> cordova build windows – --appx=uap
Running command: cmd "/s /c "...\platforms\windows\cordova\build.bat --buildConfig=...\build.json --appx=uap""
Reading build config file: ...\build.json
MSBuildToolsPath: C:\Program Files (x86)\MSBuild\14.0\bin
Building project: ...\platforms\windows\CordovaApp.Windows10.jsproj
Configuration : debug
Platform : anycpu
C:\Program Files (x86)\MSBuild\Microsoft\NuGet\Microsoft.NuGet.targets(211,5): error : Your project.json doesn't list 'win10' as a targeted runtime. You should
add '"win10": { }' inside your "runtimes" section in your project.json, and then re-run NuGet restore. [...\platforms\windows\CordovaApp.Window
s10.jsproj]
ERROR: Error code 1 for command: C:\Program Files (x86)\MSBuild\14.0\bin\msbuild with args: ...\platforms\windows\CordovaApp.Windows10.jsproj,/clp:NoSummary;NoItemAndPropertyList;Verbosity=minimal,/nologo,/p:Configuration=debug,/p:Platform=anycpu
ERROR building one of the platforms: Error: cmd: Command failed with exit code 2
You may not have the required environment or OS to build this project
Error: cmd: Command failed with exit code 2

I tried to "cordova platform rm windows" and then to add it again. No difference. If I create a new test project, add the platform and build as above it works just fine.