Created Unassigned: Windows Phone 7 project no longer compiling after upgrade to 4.3.31.0 [7633]

Just upgraded several nuget packages for Windows Phone 7 project including MVVM light libraries upgrade to 4.3.31.0.

When recompiling the project I get the following errors, could this have something to do with the upgrade of MVVM Light, or do I need to solve this problem in another way?

Windows Phone 7 does not compile, but Windows Phone 8 projects does compile without problems.

10>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3258: The primary reference "GalaSoft.MvvmLight.Extras.WP71, Version=4.3.31.28777, Culture=neutral, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the .NET Framework assembly "System.Windows, Version=2.0.6.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e" which has a higher version "2.0.6.0" than the version "2.0.5.0" in the current target framework.

10>C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(1605,5): warning MSB3258: The primary reference "GalaSoft.MvvmLight.WP71, Version=4.3.31.28777, Culture=neutral, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the .NET Framework assembly "System.Windows, Version=2.0.6.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e" which has a higher version "2.0.6.0" than the version "2.0.5.0" in the current target framework.