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When I try to update from Xamarin.Forms 126.96.36.19982 to Xamarin.Forms 188.8.131.5229 in the NuGet package manager, I get the above message when I build on the Android platform. Seems to be a know problem. See here: https://forums.xamarin.com/discussion/56957/xf-android-could-not-load-assembly-microsoft-windows-design-extensibility
Microsoft Visual Studio Professional 2015
Version 14.0.24720.00 Update 1
Microsoft .NET Framework
Installed Version: Professional
Visual Basic 2015 00325-60003-97886-AA825
Microsoft Visual Basic 2015
Visual C# 2015 00325-60003-97886-AA825
Microsoft Visual C# 2015
Visual C++ 2015 00325-60003-97886-AA825
Microsoft Visual C++ 2015
Windows Phone SDK 8.0 - DEU 00325-60003-97886-AA825
Windows Phone SDK 8.0 - DEU
Application Insights Tools for Visual Studio Package 4.2.60128.3
Application Insights Tools for Visual Studio
ASP.NET and Web Tools 2015.1 (Beta8) 14.1.11106.0
ASP.NET and Web Tools 2015.1 (Beta8)
ASP.NET Web Frameworks and Tools 2012.2 4.1.41102.0
For additional information, visit http://go.microsoft.com/fwlink/?LinkID=309563
ASP.NET Web Frameworks and Tools 2013 5.2.30624.0
For additional information, visit http://www.asp.net/
Common Azure Tools 1.5
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.
Microsoft Azure Mobile Services Tools 1.4
Microsoft Azure Mobile Services Tools
NuGet Package Manager 3.3.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.
PreEmptive Analytics Visualizer 1.2
Microsoft Visual Studio extension to visualize aggregated summaries from the PreEmptive Analytics product.
SQL Server Data Tools 14.0.50616.0
Microsoft SQL Server Data Tools
TypeScript for Microsoft Visual Studio
UWPTileGeneratorCommand Extension 1.0
UWPTileGeneratorCommand Visual Studio Extension Detailed Info
Visual Studio Tools for Universal Windows Apps 14.0.24720.00
The Visual Studio Tools for Universal Windows apps allow you to build a single universal app experience that can reach every device running Windows 10: phone, tablet, PC, and more. It includes the Microsoft Windows 10 Software Development Kit.
Xamarin 184.108.40.206 (1cc3a99)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.
Xamarin Inspector Support 0.5.0.0 (45b35bb)
Adds support for inspecting Xamarin and WPF apps.
Xamarin.Android 220.127.116.11 (46c3f7e)
Visual Studio plugin to enable development for Xamarin.Android.
Xamarin.iOS 18.104.22.168 (686b410)
Visual Studio extension to enable development for Xamarin.iOS.
Hi this is a known issue with the init.ps1 script we had in previous versions.
You just have to delete any references to Xamarin.Forms.Core.Design and Xamarin.Forms.Xaml.Design in their projects manually.
Next time you upgrade you won't have this issue.