The file size should be approximately 80 MB to 120 MB depending on the Windows version. The file name will look like: microsoft-windows-netfx3-ondemand-package.cab (sometimes with a language code like ~31bf3856ad364e35~amd64~~.cab). That’s normal.
If you get an error about the source, it means the CAB file is corrupted or the path is wrong.
You might need to download or reference microsoft-windows-netfx3-ondemand-package.cab if: Download Microsoft-windows-netfx3-ondemand-package.cab
In short: Group Policy.
If your PC is domain-joined or has been optimized to use a local WSUS server, Windows tries to pull the .NET 3.5 files from that internal server instead of Microsoft. If those files aren't approved on the server, the installation fails with a policy error.
Absolutely. That is one of the main reasons to use the offline CAB method. The file size should be approximately 80 MB
The Microsoft-windows-netfx3-ondemand-package.cab is a legitimate, useful, but dangerous-if-fake file. Its story is one of compatibility bridging old software to new operating systems. Always obtain it from a Microsoft Windows ISO or Microsoft Update Catalog. Never trust third-party downloads. Follow the DISM steps above, and you’ll enable .NET 3.5 safely.
If you tell me your exact Windows version (run winver) and architecture (64-bit or 32-bit), I can guide you to the exact Microsoft source for the file. If you get an error about the source,
After installation, check with PowerShell:
Get-WindowsFeature -Name NetFx3
Or simply open Control Panel → Programs → Turn Windows features on or off – you should see .NET Framework 3.5 (includes .NET 2.0 and 3.0) checked.
Once you have the .cab file, you have two primary methods to install it: using DISM (Deployment Imaging Servicing and Management) – the recommended approach for all users, or using PowerShell.