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Install .NET Framework 3.5 on Windows 11

.NET Framework 3.5 is supported on Windows 11. How you obtain .NET Framework 3.5 depends on which version of Windows 11 you're using. Use the following list to identify the installation method that's applicable to you:

Windows 11 Insider Preview Build 27965 and later

Starting with Windows 11 Insider Preview Build 27965, .NET Framework 3.5 is no longer available as a Windows Features on Demand optional component. Install it using a standalone installer (also known as an offline installer). For more information, see Announcing Windows 11 Insider Preview Build 27965 (Canary Channel).

For more information about this change to .NET Framework 3.5, see .NET Framework 3.5 on Windows 11 FAQ.

.NET Framework 3.5 optional components

Applies to Windows 11 Insider Preview Build 27965 and later

The following optional .NET Framework 3.5 components were previously available as Windows Features on Demand. Windows 11 Insider Preview Build 27965 removes these components:

  • ASP.NET 3.5
  • .NET Extensibility 3.5
  • WCF HTTP Activation
  • WCF non-HTTP Activation

How to enable ASP.NET 3.5 and WCF in IIS

Starting with Windows 11 Insider Preview Build 27965, ASP.NET 3.5 and WCF require additional registration to run in IIS.

Enable ASP.NET 3.5 on your device using the Enable-ASPNet35.ps1 PowerShell script. The script enables the functionality of the following optional components that have been removed from Windows:

  • ASP.NET 3.5
  • .NET Extensibility 3.5

Note

The script only restores the functionality of these optional components so that applications that depend on them can continue working. The optional components are still missing from Windows 11 and tools like DISM won't detect these optional components as present after running the script.

Prerequisites

  • Windows Insider Preview Build 27965 or later
  • Windows PowerShell 5.1
  • .NET Framework 3.5
  • The Web Server (IIS) feature or role enabled, along with the ISAPI Filters and ISAPI Extensions optional components
  • An administrative PowerShell command window

Run the script

  1. Download the Enable-ASPNet35.ps1 script to a local directory.

  2. Open a Windows PowerShell command window as Administrator.

  3. Change the execution policy to allow scripts downloaded from the Internet and signed by trusted publishers:

    Set-ExecutionPolicy RemoteSigned

    For more information about execution policy settings, see Set-ExecutionPolicy.

  4. Go to the directory where you downloaded the script.

  5. Run the script:

    .\Enable-ASPNet35.ps1

How to determine which version of Windows you're using

There are a few different ways you can find the version of Windows you're using:

  • Select this (ms-settings:about) link which might open the Settings app.

    1. Scroll down to the Windows specifications section and find the Version field.

  • Use the start menu:

    1. Press the Windows key to open the Start menu.
    2. Type Settings to find the Settings app and open it.
    3. Scroll down to the Windows specifications section and find the Version field.

  • Run the winver.exe app:

    1. Press the Windows+R keyboard shortcut to open the Run dialog.
    2. Type winver.exe and press Enter.
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