How to Install .NET Framework 3.5 on Server 2012 R2

.NET Framework

I recently ran into an issue with Windows Server 2012 R2 and was able to resolve it despite a good deal of misinformation that I found out on the Internet. It all started when I needed to install a proprietary application on one of my client’s production servers; the application in question required Microsoft .NET Framework 3.5. No biggie, I thought, remembering that this could be enabled as a “feature” through Server Manager. So I loaded it up and attempted installation only to watch it crash and burn (see image below).

Message-indicating-.NET-Framework-3.5-installation-failed-on-Windows-Server-2012-R2 I immediately checked with Microsoft for answers and was pleased to see this exact issue formally addressed here: I installed the hotfix noted in the article, but it failed to install! Furthermore, the other “workarounds” provided in the article were laughable. For example, the first one is, and I quote, “Turn on the Microsoft .NET Framework 3.5 feature before you install security update 2966827 or 2966828.” OK, sure! Let me just go hop in my time machine! Also, I considered simply removing KB2966827 and KB2955828, however these are very important security updates that patch critical vulnerabilities – something I definitely want on my production server. I thought it over for a while, and had a look at the error again. The error states “The source files could not be found.” I grabbed a Server 2012 R2 installation media that I had laying around and checked the SxS folder – sure enough, .NET Framework 3.5 was nowhere to be found! However, this gave me an idea: I headed over to Microsoft’s Software Evaluation Center: and downloaded an evaluation copy of Server 2012 Standard (Not R2!). Once the download completed, I mounted the ISO file and confirmed that the .NET Framework 3.5 package was present in the Sources\SxS folder. I then copied this entire folder to the production server in question and was able to run through the feature installation process again. But this time, I selected the previously copied SxS folder as my source (see image below). specify-alternate-path-for-.NET-Framework-3.5 And this is what finally allowed me to successfully install .Net Framework 3.5 on Windows server 2012 R2. It’s such a simple thing, I’m left wondering why Microsoft doesn’t just release the source package for download on their website somewhere (perhaps as a solution in the above mentioned article).

Brian Dunham is a Cisco and Microsoft certified network and systems engineer with over a decade of experience in the Information Technology field. When he is not in front of a computer he can be found out in the wilderness canoing, hiking, fishing, or camping.


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