Mailbag: Does my application need to install the .NET Framework 4 on Windows 8 or Windows Server 2012?

Question:

I have an application that requires the .NET Framework 4. The application supports running on Windows 8 and Windows Server 2012, which both include the .NET Framework 4.5 as a part of the operating system. Does my application installer still need to install the .NET Framework 4 on these operating systems even though the .NET Framework 4.5 is already installed?

Answer:

No. The .NET Framework 4.5 is a full in-place update for the .NET Framework 4. Applications that require the .NET Framework 4 will run correctly if the .NET Framework 4.5 is installed on the computer. In addition, the installer for the .NET Framework 4 will prevent you from attempting to downgrade a computer that already has the .NET Framework 4.5 back to the .NET Framework 4.

For more detailed information about .NET Framework 4.5 installation scenarios like this, please refer to this MSDN topic.