.NET: Microsoft Technologies based on the .NET software framework. Runtime: An environment required to run apps that aren't compiled to machine language.
On Windows 11, this depends on the Windows version:
- Check the Windows version first:
- Press
Windows + R - Run
winver.exe - If the version is Windows 11 26H1 (build 28000) or later,
.NET Framework 3.5will not appear in Turn Windows features on or off.
- Press
- If the device is Windows 11 26H1 (build 28000) or later:
-
.NET Framework 3.5is only available as a standalone installer. - It can no longer be installed as a Windows component.
- Use:
- Important: these installers only work with the specified Windows version.
-
- If the device is Windows 11 25H2 or earlier:
- Open Windows Features.
- Select .NET Framework 3.5 (includes .NET 2.0 and 3.0).
- Select OK.
- Restart if prompted.
- If ASP.NET 3.5 is needed in IIS on Windows 11 26H1 or later:
- Install
.NET Framework 3.5first. - Enable IIS with ISAPI Filters and ISAPI Extensions.
- Run the
Enable-ASPNet35.ps1script from an Administrator PowerShell 5.1 window.
- Install
Also, on Windows 11 26H1 and later, these optional components were removed from Windows Features:
- ASP.NET 3.5
- .NET Extensibility 3.5
- WCF HTTP Activation
- WCF non-HTTP Activation