If you are working in an environment without internet access or frequently encounter errors like or 0x800f081f when using the standard Windows Update method, you will need an offline installation strategy. Official Offline Installer Options
:The most reliable "offline installer" for Windows 10 is actually hidden within your Windows 10 ISO or installation USB. This method is preferred because it ensures the framework version perfectly matches your specific Windows 10 build. How to Install .NET 3.5 Offline via DISM (CMD)
Microsoft provides two primary ways to obtain the .NET Framework 3.5 offline: If you are working in an environment without
Download .NET Framework 3.5 Windows 10 64-Bit Offline Installer
: Type the following command, replacing D: with your actual drive letter: How to Install
: Right-click your ISO file and select Mount , or insert your Windows 10 USB drive.
: Note the drive letter of the mounted media (e.g., D: or E: ). This is a "full package" (approx
:You can download the full service pack package directly from the Official Microsoft Download Center . This is a "full package" (approx. 231 MB) that does not require an active internet connection during the installation process once downloaded.
If you have a Windows 10 ISO or USB drive, follow these steps to install the framework without using any data: