Technical Brief: Offline Installation of .NET Framework 3.5 on Windows 10 (64-bit)

Prepared for: System Administrators and Advanced Users
Date: Current
Subject: Sourcing and deploying .NET Framework 3.5 (includes 2.0 & 3.0) without an internet connection.

Is .NET Framework 3.5 safe to install alongside version 4.8?

Yes. They run side-by-side without conflict. In fact, many apps require both.

Option 3: Using Windows Features (If You Have Installation Media)

  1. Press Win + R, type control and hit Enter.
  2. Go to Programs → Turn Windows features on or off.
  3. Check the box for .NET Framework 3.5 (includes .NET 2.0 and 3.0).
  4. Click OK. If an internet download fails, Windows will ask for an alternate source – point it to your sxs folder.

Can I slipstream .NET 3.5 into a Windows 10 installation USB?

Yes. Use DISM to mount your Windows image (install.wim) and add the feature offline. That way, every new PC gets it pre-installed.

What about a standalone offline installer for Windows 10 32-bit?

The methods above work identically for 32-bit (x86) systems, just ensure your source ISO matches your architecture.

Quick summary (step-by-step)

  1. Mount matching Windows 10 ISO or insert installation USB.
  2. Open elevated Command Prompt.
  3. Run: 
    DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /Source:X:\sources\sxs /LimitAccess
    (replace X: with your drive letter)
  4. Verify feature is enabled.

If you want, I can provide the exact DISM/PowerShell commands tailored for your drive letter and Windows build.

Installing .NET Framework 3.5 on Windows 10 (64-bit) without an active internet connection typically requires using Windows 10 installation media (such as an ISO file or USB drive) or the official Standalone Installer if you can download it beforehand from another machine. Method 1: Using Windows 10 Installation Media (Recommended)

Windows 10 already contains the files needed for .NET 3.5 in its installation media, specifically within the sources\sxs folder.

Mount your Windows 10 ISO or insert your installation USB drive.

Open This PC and note the drive letter assigned to the media (e.g., D: or E:).

Right-click the Start button and select Command Prompt (Admin) or Windows PowerShell (Admin).

Enter the following command, replacing D: with your actual drive letter:DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs

Wait for the progress bar to reach 100%. Once completed, you will see a "The operation completed successfully" message. Method 2: Official Standalone Installer

If you have access to another computer with internet, you can download the full offline package and transfer it to your offline machine via USB. How To Install .Net Framework 3.5 Offline On Windows 10

5. Important Considerations

| Factor | Detail | |--------|--------| | Architecture | The sxs folder contains both 32-bit and 64-bit packages. The DISM command automatically detects the correct one for your 64-bit OS. | | No Microsoft-provided single EXE | Any website offering a standalone dotnetfx35.exe claiming "for Windows 10 64-bit offline" is likely unofficial and potentially risky. Always use the official ISO source. | | Verification | After installation, verify via Control Panel → Programs and Features → "Turn Windows features on or off" – .NET Framework 3.5 should be checked. |