1. Error: 0x800f0954 or 0x800F081F
This usually happens if Windows Update is disabled or if the system cannot access the update servers. Using the DISM command with the local .cab file (Method above) usually solves this.
2. "The source files could not be found"
If you try to install using the "Turn Windows features on or off" menu without internet, you will see this. You must use the Command Prompt (DISM) method pointing directly to the .cab file you extracted from the ISO.
3. File Version Mismatch
Ensure the .cab file comes from the exact same version of Windows you are running.
Use DISM /Mount-Image, then DISM /Add-Package, then DISM /Commit-Image to inject the CAB directly into install.wim. Microsoft-windows-netfx3-ondemand-package.cab Download
While Windows 10 and 11 come with .NET Framework 4.x pre-installed, they do not include .NET 3.5 by default. Microsoft treats it as an "optional feature on demand" (FOD). You need it because:
Without this .cab file, Windows will try to download the feature from Windows Update. If your PC is offline, behind a corporate firewall, or if Windows Update is broken, the installation will fail – hence the need for the offline .cab package.
Search for “NETFX3” on the official Microsoft Update Catalog. Look for the package matching your Windows version (e.g., “Feature On Demand for Windows 10 Version 22H2”). Use DISM /Mount-Image , then DISM /Add-Package ,
Step 1: Place the CAB file in an easy-to-access folder. For this guide, we’ll assume it’s C:\temp\.
Step 2: Rename the file (optional) to something shorter, e.g., netfx3.cab. This reduces typing errors.
Step 3: Open Command Prompt as Administrator. While Windows 10 and 11 come with
Step 4: Run the following DISM command:
DISM /Online /Add-Package /PackagePath:C:\temp\netfx3.cab
Step 5: Wait for the process to complete. It will show a progress bar. When done, you’ll see: “The operation completed successfully.”
Step 6: Restart your PC (even if not prompted, it’s good practice).