If you have a Windows ISO or USB, you can install it offline from the sources\sxs folder: DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:D:\sources\sxs (where D: is your drive letter).
Note: If the filename is longer (e.g., including ~31bf3856ad364e35~amd64~~ ), you must use the full filename. Once the process reaches 100%, restart your computer. Alternative DISM Method (using sxs folder)
: The package version must match your OS version (e.g., a package from Windows 10 1909 may not work on Windows 10 2004). Installation Instructions
Use the trusted open-source tool “UUP dump” to generate a genuine Windows CAB file from Microsoft’s public servers. Microsoft-windows-netfx3-ondemand-package.cab Download
Windows 10 and 11 come pre-installed with newer versions of .NET, like version 4.8. However, they don't include the full binaries for version 3.5 by default to save disk space. The microsoft-windows-netfx3-ondemand-package.cab file contains the exact engine your computer needs to run apps built on .NET 2.0 through 3.5. Where to Safely Download It
If you are in an "air-gapped" environment (no internet) or dealing with a PC that has Windows Update restricted by group policy, you need the .cab file. Where to Download the .NET 3.5 CAB File
: The ~31bf3856ad364e35~ is the Microsoft public key token. The architecture and build number are embedded. If you have a Windows ISO or USB,
/LimitAccess : Prevents DISM from trying to contact Windows Update. Troubleshooting Common Errors
Show you how to verify the to prevent compatibility errors.
⚠️ : Downloading .cab files from third-party websites poses security risks. Always verify file hashes from Microsoft-signed sources. Alternative DISM Method (using sxs folder) : The
Once you have located or copied the Microsoft-Windows-NetFx3-OnDemand-Package.cab file to your local drive, you must use the Deployment Image Servicing and Management (DISM) tool to install it. Traditional double-clicking will not work. Follow these steps to complete the installation: Step 1: Prepare the File Path
: If you have a Windows ISO or USB installer, mount it and navigate to the \sources\sxs\ folder. The file is located there. Version Sensitivity
After the progress bar reaches 100%, you should see the message: "The operation completed successfully." To verify: Open the dialog box (Press Win + R ). Type optionalfeatures and hit Enter.
If you have already downloaded the microsoft-windows-netfx3-ondemand-package.cab file, you can install it using the tool. Open Command Prompt as an Administrator.