Installing .Net 3.5 on Windows 8

If you have recently downloaded and installed Windows 8 RTM, you may begin finding applications that require the usage of .Net Framework v. 3.5.

Unfortunately, unlike its predecessor--Windows 7, Windows 8 ships with .Net v. 4.5.

Well, that poses a bit of a problem because of the new installation infrastructure that was implemented with Windows 8 whereby the installation media/installation source is required when installing any additional Windows features.  This new mechanism of installation is called DISM and you can read more about it here: http://technet.microsoft.com/en-us/library/hh824821.aspx

If you encounter and read this article regarding DISM and .Net 3.5, you will see that it primarily addresses the issue in Windows Server 2012 and only provides a cursory overview of how to solve it in Windows 8: http://blogs.technet.com/b/askcore/archive/2012/05/14/windows-8-and-net-framework-3-5.aspx

The key to installing .Net 3.5 on Windows 8 actually lies in the first few steps:

1. Open up gpedit.msc
2. Edit the Group Policy under Computer Configuration-->Administrative Templates-->System
3. Open the policy for Specify settings for optional component installation and repair.
4. Specify an alternate source file path for the files (preferably a file path directly to the ISO image/Windows 8 media).  You can also optionally check the checkbox for "Never attempt to download payload from Windows Update"
5. Click OK to close the Group Policy Editor
6. Now open Control Panel-->Programs and Features
7. Click on "Turn Windows Features on or off" in the left hand navigation
8. Click on the checkbox for ".NET Framework 3.5 (includes .NET 2.0 and 3.0)
9. Click the OK button to proceed with the installation

If all goes well, you should be able to successfully install .NET 3.5 on your Windows 8 RTM machine!