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# Steps to reproduce
1. Open a Xamarin.Forms app (in this case, I did File -> New Project -> Cross-Platform -> Cross-Platform App).
2. Open a xaml file and add a button.
3. Attempt to generate a click handler for that button.
# Expected behavior
Click handler is generated without error.
# Actual behavior
Click handler throws an error "Ensure event failed". Attempting to create this event the second time succeeds.
# Supplemental info (logs, images, videos)
Environment Information: https://gist.github.com/pierceboggan/b19b77773aba683649587ceed6f794ac
Created attachment 23859 [details]
I can confirm using the latest Visual Studio 2017 Preview version 15.3 I am able to reproduce this issue. Marking this report as CONFIRMED.
# Version information
Microsoft Visual Studio Enterprise 2017 Preview
Version 15.3.0 Preview 6.0
Microsoft .NET Framework
Installed Version: Enterprise
Visual Basic 2017 00369-60000-00001-AA758
Microsoft Visual Basic 2017
Visual C# 2017 00369-60000-00001-AA758
Microsoft Visual C# 2017
Visual F# 4.1 00369-60000-00001-AA758
Microsoft Visual F# 4.1
Application Insights Tools for Visual Studio Package 8.8.00712.1
Application Insights Tools for Visual Studio
ASP.NET and Web Tools 2017 15.0.30718.0
ASP.NET and Web Tools 2017
ASP.NET Core Razor Language Services 1.0
Provides languages services for ASP.NET Core Razor.
ASP.NET Template Engine 2017 15.0.30718.0
ASP.NET Template Engine 2017
Common Azure Tools 1.10
Provides common services for use by Azure Mobile Services and Microsoft Azure Tools.
Merq 1.1.17-rc (cba4571)
Command Bus, Event Stream and Async Manager for Visual Studio extensions.
Microsoft Visual Studio VC Package 1.0
Microsoft Visual Studio VC Package
Mono Debugging for Visual Studio 4.6.8-pre (ec7034f)
Support for debugging Mono processes with Visual Studio.
NuGet Package Manager 4.3.0
NuGet Package Manager in Visual Studio. For more information about NuGet, visit http://docs.nuget.org/.
TypeScript tools for Visual Studio
Visual Studio Code Debug Adapter Host Package 1.0
Interop layer for hosting Visual Studio Code debug adapters in Visual Studio
Visual Studio Tools for Universal Windows Apps 15.0.26720.02
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 188.8.131.525 (306f76a)
Visual Studio extension to enable development for Xamarin.iOS and Xamarin.Android.
Xamarin.Android SDK 184.108.40.206 (0cd0214)
Xamarin.Android Reference Assemblies and MSBuild support.
Xamarin.iOS and Xamarin.Mac SDK 10.12.0.14 (bf350ba)
Xamarin.iOS and Xamarin.Mac Reference Assemblies and MSBuild support.
Are there any news with this issue? Its frustrating to make every event handler by hand.
We're currently looking into the issue. It appears it might be a generic issue with XAML editing that we need to pass on to that team, as it is appearing in UWP and WPF projects as well.
For me this starts happening for some reason. Previously when this problem appeared, I updated xamarin, restarted vs and somehow it went away. Now it again came.
This time it went away just by restarting VS.
This is a confirmed issue in the Visual Studio DTE. We've alerted that team of the issue, and they are investigating a fix.
Marking as RESOLVED-UPSTREAM.
I've declared some delegates before class in code behind and then the error happened. After changing the delegates after class, the error stopped.