Visual-studio – Project could not be opened because the Microsoft Visual C# 2010 compiler could not be created. Please re-install Visual Studio

• None: The file is not included in the project output group and is not compiled in the build process. An example is a text file that contains documentation, such as a Readme file.

• Compile: The file is compiled into the build output. This setting is used for code files.

• Content: Allows you to retrieve a file (in the same directory as the assembly) as a stream via Application.GetContentStream(URI). For this method to work, it needs a AssemblyAssociatedContentFile custom attribute which Visual Studio graciously adds when you mark a file as "Content"

• Embedded resource: Embeds the file in an exclusive assembly manifest resource.

• Resource (WPF only): Embeds the file in a shared (by all files in the assembly with similar setting) assembly manifest resource named AppName.g.resources.

• Page (WPF only): Used to compile a xaml file into baml. The baml is then embedded with the same technique as Resource (i.e. available as `AppName.g.resources)

• ApplicationDefinition (WPF only): Mark the XAML/class file that defines your application. You specify the code-behind with the x:Class="Namespace.ClassName" and set the startup form/page with StartupUri="Window1.xaml"

• SplashScreen (WPF only): An image that is marked as SplashScreen is shown automatically when an WPF application loads, and then fades

• DesignData: Compiles XAML viewmodels so that usercontrols can be previewed with sample data in Visual Studio (uses mock types)

• DesignDataWithDesignTimeCreatableTypes: Compiles XAML viewmodels so that usercontrols can be previewed with sample data in Visual Studio (uses actual types)

• EntityDeploy: (Entity Framework): used to deploy the Entity Framework artifacts

• CodeAnalysisDictionary: An XML file containing custom word dictionary for spelling rules

I was running into this problem as well. I was able to resolve the issue by running
sn -i <KeyFile> <ContainerName> (installs key pair into a named container).

sn is usually installed as part of a Windows SDK. For example C:\Program Files (x86)\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools\sn.exe. Most likely this location is not on the search path for your standard environment. However, the "Developer Command Prompt" installed by Visual Studio adds additional information that usually includes the correct location.

Based on your post that would look like

sn -i companyname.pfx VS_KEY_3E185446540E7F7A

This must be run from the location of your PFX file, if you have the solution loaded in VS 2010 you can simply right click on the pfx file from the solution explorer and choose Open Command Prompt which will launch the .net 2010 cmd prompt tool in the correct directory.

Before running this sn command I did re-install the pfx by right clicking on it and choosing install however that did not work. Just something to note as it might be the combination of both that provided the solution.

Hope this helps solve your problem.