God, why is this so difficult? I needed to install the .NET framework 3.5 (for SQL Management Studio, dammit!) on my Windows 8.1 machine. You’re supposed to be able to do this from control panel (Programs and Feature > Turn on Windows Features > .Net 3.5). It didn’t work for me.
I found myself looking at the troubleshooting section. My PC does not appear to have KB2966826, KB2966827 or KB2966828 installed, but it was just like it had that issue. I tried the security update 3005628 as described; that failed to run. Apparently it didn’t apply to me. I guess I didn’t have those updates installed.
(Trying to update an update. Very meta.)
The error message windows was giving me said that I’d no Internet Connection (a lie) so out of desperation I set off in search of the original installation media for Windows 8.1 (just as well that this is a clean, 2 week-old machine, and I know where the disc was). I then opened a command prompt as Adminstrator, and ran:
DISM /Online /Enable-Feature /FeatureName:NetFx3 /All /LimitAccess /Source:installationMediaDrive:\sources\sxs
This copied the .NET framework 3.5 from the DVD, and installed the Framework that way.
Good God, this was epic, and I can only describe it as an epic fail from MS.