[UPDATED ON 2019 JAN 25]

Make sure the Windows 8 disk is in the drive (if your drive is not the d:\ drive, change the source drive letter to match your drive)

dism.exe /online /enable-feature /featurename:NetFX3 /Source:d:\sources\sxs

The install will take a few minutes to run.

Note* – If Windows update service is disabled , enable it before run the command other wise you will get more errors like Error: 0x800f081f

NEW UPDATE –

IF YOUR HAVING BUILD VERSION 1806 USE THE SAME BUILD DVD TO INSTALL THE FEATURE

TRY THIS COMMAND IF ABOVE COMMAND IS NOT WORKING

Dism.exe /online /enable-feature /featurename:NetFX3 /source:d:\sources\sxs /LimitAccess