/enable-feature /featurename:NetFX3 : Tells Windows to turn on the .NET Framework 3.5 feature.
Method 2: Create a Standalone .NET 3.5 Offline Installer Script
If you encounter errors during the offline installation, try the following solutions:
https://download.microsoft.com/download/6/0/f/60fc5854-3cb8-4892-b6db-bd4f42510f28/dotnetfx35.exe
If you don't have the ISO, you can force Windows to use the component store already on your drive, but this still requires the component to be pre-cached. If the previous methods failed, you can try this command: Open .