Open the Start menu, type cmd , right-click Command Prompt , and select Run as Administrator .

For Windows 11 (Build 28000 and later), Microsoft has transitioned .NET 3.5 to a standalone deployment . You can download the .NET Framework 3.5 Service Pack 1 (Full Package) directly from the Official Microsoft Download Center Offline DISM Method:

You do not need to purchase software or use risky third-party download portals to get the .NET Framework 3.5 offline installer. By utilizing the DISM tool alongside your original Windows 10 or 11 installation media, you can safely enable this framework on any offline computer completely free of charge.

When you try to run an older app, you will often see a popup stating, "An app on your PC needs the following Windows feature: .NET Framework 3.5 (includes .NET 2.0 and 3.0)." If your computer has a stable internet connection, Windows can download these files automatically. However, if you are working offline, managing multiple deployments, or facing Windows Update errors, you will need an offline installer.

Type and click OK to open the Windows Features menu.

.NET Framework 3.5 remains a critical component for running legacy applications and games on modern operating systems like Windows 10 Windows 11

How to Download .NET Framework 3.5 Offline Installer for Windows 10/11 (Free)