Programatically check for version .NET Framework - Should I?

Question

I got at task to extend en existing WinForm application to make a check weather or not the required .NET Framework (fx. 3.5) is installed.

Well the issues is that - if there is no .NET Framework installed, the winform program is not able to run at all... I assume.

I could (maybe) do like suggested here: (and make a c++ program that should start first, make the check and then launch the application) Check on .Net framework version from WinForms app But I would rather not go into c++.

Another way seems to be this solution: Why isn't an exception thrown when the right .NET framework version is not present? ... where you configure your application in app.config. But I doubt that will work if there i no .NET framework installed.

<startup>
    <supportedRuntime version="v3.5" />
</startup>

So my question is what is Best Practice in this area? Should I make the check one way or the other, or should I just make it a pre-requisite, that fx. .NET Framework version 3.5 is demanded?

Answer 1

If the required framework is not installed, your application won't run, so checking if the framework is installed from within your app is checking something you already know to be true.

If you want to check that the framework is installed, you really need to do this from within a a bootstrapper exe either written in a .NET version you know will exist (like .NET 2 as it gets installed on the machine with the OS) or some other language like C++.

You can check in the registry (HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP) to see what frameworks are installed. This can easily be done in C# or any other language.

C# code something like this:

var baseKeyName = @"SOFTWARE\Microsoft\NET Framework Setup\NDP";
var installedFrameworkVersions = Registry.LocalMachine.OpenSubKey(baseKeyName);

var versionNames = installedFrameworkVersions.GetSubKeyNames();