For legacy operating systems like Windows 7 SP1 and Windows Server 2008 R2 SP1, the system must have the update installed prior to running the setup. This is delivered via KB4019990. Without this update, the .NET Framework installation will fail with a fatal initialization error. Step-by-Step Installation Process
: Essential for restoring functionality to enterprise applications hosted on closed intranet networks. Web Installer vs. Offline Installer Comparison microsoft net framework 462 offline installer hot
That is the , not the web bootstrapper.
If you are considering which .NET Framework version to install, here is a quick comparison: For legacy operating systems like Windows 7 SP1