.NET 3.5 Framework
Integrate .NET 3.5 into images or install it on already deployed systems.
.NET Framework 3.5 is required by many applications but is not enabled by default in modern Windows. This guide covers integrating it into an image before deployment, installing it on an already running system, and the separate installer Windows 11 26H1 uses.
Integrate .NET 3.5 into an Image
To offline integrate .NET Framework 3.5 into a Windows 10/11 image:
- Load an image - use full ISO content extracted to a folder
- Go to the Updates page
- Click Add → Templates → .NET 3.5 Framework
- Go to Apply → Process
Note: NTLite automatically pulls the needed .NET 3.5 package from the loaded image's source files. No separate download is required.
Install .NET 3.5 on a Deployed System
To install .NET 3.5 on an already deployed Windows system using NTLite:
- On the Start page, go to toolbar Tools → Install Updates
- Click Add → File
- Select the .NET 3.5 CAB from the ISO that matches your deployment:
.\sources\sxs\microsoft-windows-netfx3-ondemand-package~31bf3856ad364e35~amd64~~.cab - Go to Apply → Process
Important: The ISO must match the Windows version and build number of the deployed system. For 32-bit systems, use the x86 variant of the CAB file instead of amd64.
Windows 11 26H1
From Windows 11 26H1 (build 28000), Microsoft ships .NET 3.5 as a standalone installer, KB5087077, with a separate language pack installer. NTLite downloads both like any update and runs them at the end of Windows setup, before the first sign-in. The Templates entry above does not appear on a 26H1 image. Windows 11 26H2 (build 26300) keeps the method above.
- Load a 26H1 image
- Go to the Features page, Features on Demand tab, and tick .NET Framework 3.5 in the Other card. Tick its Language Pack row too for a non-English Windows
- Or on the Updates page, open Add → Latest online updates and tick KB5087077 (and its language pack) on the .NET Framework card
- Go to Apply → Process
The language pack follows the Windows display language and any language packs the image holds, so it also serves an English image with languages added. Ticking it ticks the main installer too, since it cannot install on its own.
On a running 26H1 PC, the same rows install .NET 3.5 right away when you Process, with the installer's progress window.
Important: .NET 3.5 installed this way does not survive an in-place upgrade to the next Windows release; install it again afterwards. ASP.NET 3.5, .NET Extensibility 3.5 and WCF Activation are not part of it.
Without the update list: download DotNet35Setup.exe from Microsoft's .NET Framework 3.5 page, add it on the Post-Setup page, and set its parameters to /quiet /norestart. For a non-English Windows, add the language pack installer DotNet35LPSetup.exe the same way, below it.