How to get the .NET Framework Version and ASP.NET Version

.NET Framework consists of two main components, which are versioned separately:

A set of assemblies, which are collections of types and resources that provide the functionality for your apps. .NET Framework and the assemblies share the same version number. For example, .NET Framework versions include 4.5, 4.6.1, and 4.7.2.

The common language runtime (CLR), which manages and executes your app’s code. A single CLR version typically supports multiple .NET Framework versions. For example, CLR version 4.0.30319.xxxxx where xxxxx is less than 42000, supports .NET Framework versions 4 through 4.5.2. CLR version greater than or equal to 4.0.30319.42000 supports .NET Framework versions starting with .NET Framework 4.6.

To know the CLR version. Open IIS and click on the Application Pool. You will get the default CLR version installed. Here it is v2.0 and v4.0

To get the ASP.NET Version use the following on page load. It will reveal both .NET Framework version and ASP.NET version

 protected void Page_Load(object sender, EventArgs e)
    {
        Trace.IsEnabled = true;
        btnversion.Visible = false;
    }