4] Install .NET Framework 3.5 using Windows Features (for Windows 10 Only) If you are unable to install .NET Framework successfully using an installer, Windows 10 users can try installing .NET ...

For the most part, you don’t need to worry about the version of .NET installed on your Windows 11/10 computer. Some applications require a specific release to run.

Windows Server 2008 x64, two of them in fact in an NLB cluster. Trying to install .NET Framework 4, first went fine, second refuses.