: Place the microsoft-windows-netfx3-ondemand-package.cab file in a simple directory, such as the root of your C: drive ( C:\ ).
You do not need shady "free download" websites. The CAB file is already hidden inside your Windows installation media. Here is how to extract it for free: microsoftwindowsnetfx3ondemandpackagecab extra free
Alternatively, for modern Windows 10/11 management, you can simply use the settings menu to stop Windows from keeping these installation files handy, though this usually requires a Group Policy change to prevent Windows from re-downloading them automatically. : Place the microsoft-windows-netfx3-ondemand-package
If you have the file (either from your installation media or a trusted source), use the tool to install it manually. Copy the .cab file to your C:\ drive for easy access. Open Command Prompt as an Administrator. Here is how to extract it for free:
Grab the CAB from a Windows ISO, run the single DISM command above, and move on with your day.