Follow these steps if you keep getting errors when attempting to install .NET 3.5 or 2.0 on Windows Servers.
Search – cmd – Run As Administrator – Type:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All
If it still fails, load your installer disc and type:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:d:\sources\sxs
Alternatively, you can use Powershell:
Install-WindowsFeature Net-Framework-Core -source \\network\share\sxs #or D:\sources\sxs. Run get-windowsfeature afterwards to make sure it installed.