Check if a Firewall or Antivirus is blocking Windows Update.

This is the most common error when trying to install .NET 3.5. It usually means Windows is unable to connect to the Windows Update servers. To fix this: Ensure your internet connection is stable.

Because they share the same architecture, Microsoft bundled them into a single installer to ensure total backward compatibility. When you install 3.5, you are effectively installing the engines for 2.0 and 3.0 at the same time. How to Download and Install .NET Framework 3.5

Press the , type Turn Windows features on or off , and hit Enter.

Use the via Command Prompt (Admin) to install it from a Windows installation media (USB/ISO). Do I need .NET 4.8 too?

If you are working on a machine without an active internet connection or need to deploy it across multiple computers, you can use the standalone installer.