You insert your original installation media, run the "Add Roles and Features" wizard, and point it to the sxs folder. Sometimes it works. Often, it fails with cryptic error codes like 0x800f081f (source not found). This is where the microsoftwindowsnetfx3ondemandpackagecab becomes your best friend.
: Open an elevated Command Prompt and execute the following: You insert your original installation media, run the
Note: URLs change. Search the Microsoft Update Catalog for netfx3 cab server 2012 r2 . The CAB is typically named microsoft-windows-netfx3-ondemand-package~31bf3856ad364e35~amd64~~.cab . You insert your original installation media
: After installation, the source media can be unmounted; the feature remains active in the local component store. Conclusion the source media can be unmounted