Despite the progression to .NET 4.x and the modern .NET (5+), version 3.5 remains a necessary runtime for legacy line-of-business applications. For system administrators and power users, the challenge arises when installing this feature on modern hardware (Windows 10/11 or Windows Server 2016/2019/2022). By default, these operating systems treat .NET 3.5 as an optional "Feature on Demand" (FoD).
Execute the following command (replace X: with the drive letter of the mounted media): net framework offline installer 3.5
This method often resolves issues where the mounted ISO is read with instability by the DISM tool. Despite the progression to