Fixing the Xamarin installation after uninstalling the "Xamarin Shell" extension from "Tools -> Extensions and Updates" in Visual Studio

XShellUninstallVS.txt

If you uninstall the "Xamarin Shell" extension from "Tools -> Extensions and Updates" in Visual Studio, you will get a "'ShellPackage' package did not load correctly" error even after uninstalling and re-installing both Xamarin VS extensions.


## Cause

Uninstalling the "Xamarin Shell" from "Tools -> Extensions and Updates" sets a value on [1] named "Mono.VisualStudio.Shell,1.0", with the data:
C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO 12.0\COMMON7\IDE\EXTENSIONS\XAMARIN\SHELL\1.0.0\

[1] Computer\HKEY_CURRENT_USER\Software\Microsoft\VisualStudio\12.0\ExtensionManager\PendingDeletions


Based on the label "PendingDeletions", it sounds like Visual Studio should remove the "Mono.VisualStudio.Shell,1.0" registry value once the "Xamarin Shell" extension has been uninstalled. But instead, as soon as this value is present, no amount of uninstalling and reinstalling Xamarin, restarting Visual Studio, or deleting things from the "%LOCALAPPDATA%\Microsoft\VisualStudio" directory can remove it.

As a consequence, although the Xamarin.Android installer successfully copies the "Xamarin Shell" into the Extensions directory, Visual Studio never registers it. For example, after the installation "Xamarin Shell" does not appear in the "Tools -> Extension and Updates" list, but Xamarin.Android does.


## Workaround / steps to repair the broken installation

Open `regedit` and delete the PendingDeletions -> Mono.VisualStudio.Shell,1.0 registry value. Then from an elevated command prompt run:
"C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe" /setup /nosetupvstemplates

In my case that fixes the problem, so hopefully there's no need to re-install either of the Xamarin VS extensions.


## Full steps to reproduce

1. Uninstall the "Xamarin Shell" extension from "Tools -> Extensions and Updates".

2. Quit Visual Studio.

3. Uninstall both Xamarin.Android and Xamarin.iOS from the add/remove programs Control Panel.

4. Delete the "Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\Extensions\Xamarin" folder, if there is one. 

5. Install Xamarin.Android.

6. Launch Visual Studio.


## Error messages

Here are some of the error messages. These seem to be all the same ones you would get if you accidentally deleted the "Extensions\Xamarin\Xamarin Shell" folder.

### From the dialog that pops up when Visual Studio is loading:

The 'ShellPackage' package did not load correctly.

The problem may have been caused by a configuration change or by the installation of another extension. You can get more information by examining the file 'C:\Users\username\AppData\Roaming\Microsoft\VisualStudio\12.0\ActivityLog.xml'.

### From ActivityLog.xml

SetSite failed for package [ShellPackage]
The composition produced multiple composition errors, with 3 root causes. The root causes are provided below. Review the CompositionException.Errors property for more detailed information.

----

The 3 root causes are all "No exports were found that match the constraint", one each for these three ContractNames:
> ContractName    Mono.VisualStudio.Extension.Commands.ICommandManager
> ContractName    Mono.VisualStudio.Extension.Events.IShellEvents
> ContractName    Mono.VisualStudio.Extension.Diagnostics.IUserMessageService

Thanks Brendan.. fix heped me.

Thanks

Thank You Helped Alot!