This method typically requires an internet connection to download files. However, if your system image was pre-configured with the payload, it might work offline. Microsoft Learn
Mount the ISO file (right-click -> Mount) or plug in the USB stick. Note the drive letter (e.g., D: , E: , F: ).
Verify your DISM command drive letter matches the exact location of the \sources\sxs directory. This method typically requires an internet connection to
Visit the official Microsoft Download Center for the .NET Framework 3.5 SP1 Full Package. Download the .exe file. Run the installer on your offline machine.
If the computer can be temporarily connected to a network, the easiest way to add .NET 3.5 is through the graphical interface. Press Windows Key + R to invoke the Run dialog box. Note the drive letter (e
The progress bar will reach 100%. Once finished, you’ll see a message saying "The operation completed successfully." You don't even need to restart! Alternative: The "Windows Features" Method
Check the box for . Click OK and let Windows download the necessary files. Pro-Tip for Troubleshooting Download the
Follow the prompts. If it asks for an internet connection, allow it – it will still work offline after the initial download.
This is the most reliable "free" offline method. It uses the files already present on a Windows ISO or USB drive. Microsoft Learn Prepare the Source If you have a Windows ISO file, right-click it and select Note the drive letter assigned (e.g., Open Command Prompt : Press the Start button, type , right-click it, and select Run as Administrator Run the DISM Command : Type the following command, replacing with your actual drive letter:
If the offline installation fails, it is usually due to one of these reasons:
This is the best method for a true offline install. You will need a Windows 10 or Windows 11 USB drive or ISO file.
