Haven’t posted in a while! Ran across this problem today. I needed to install .NET 3.5 for some legacy software on my Windows 10 VM. I have had to go through this process in the past for other things.
This can happen when using a WSUS server on your domain – the dreaded 0x8024401C error when trying to install 3.5 as a feature.
The quick workaround I have used is to turn off WSUS via the registry temporarily, then run the add feature again.
HKEY_Local_Machine\Software\Policies\Microsoft\Windows – Delete the entire WindowsUpdate key (looks like a folder)
Open services.msc and restart Windows Update.