Required or recommended
For GN4 versions 2.6 or newer, the .NET Framework 4.7 is required.
For GN4 versions 2.3 or newer, the .NET Framework 4.6.1 is required.
For GN4 versions 2.2 or newer, the .NET Framework 4.5.2 is required.
For GN4 versions 2.1, the .NET Framework 4.5.1 is required, and the .NET Framework 4.5.2 is recommended.
For GN4 versions 2.0 and 1.6, the .NET Framework 4.5 is required.
Preinstalled defaults
Framework 4.6 is installed by default on the Microsoft Windows 10.
Framework 4.5.1 is installed by default on the Microsoft Windows 2012 R2 server and on the Windows 8.1 computers.
Framework 4.5 is installed by default on the Microsoft Windows 8.
Download links
Link to Framework 4.6.1 Web installer:
https://www.microsoft.com/en-us/download/details.aspx?id=49981
or Offline installer
https://www.microsoft.com/en-us/download/details.aspx?id=49982
Link to Framework 4.5.2:
http://www.microsoft.com/en-us/download/details.aspx?id=42643
Link to Framework 4.5.1:
http://www.microsoft.com/en-us/download/details.aspx?id=40773
Link to Framework 4.5:
http://www.microsoft.com/en-us/download/details.aspx?id=30653
Link to Framework 4:
http://www.microsoft.com/download/en/details.aspx?id=17851
To determine which version of the .NET Framework is currently installed, follow the procedure as explained in How to: Determine Which .NET Framework Versions Are Installed and How to: Determine Which .NET Framework Updates Are Installed on the MSDN Web site.
About ended support of Framework 4, 4.5 and 4.5.1:
http://blogs.msdn.com/b/dotnet/archive/2015/12/09/support-ending-for-the-net-framework-4-4-5-and-4-5-1.aspx
Miles33 still has GN4 2.0 and 2.1 running on these frameworks, but no action is required by existing customers running these builds.
In case of installation of these builds on new machines, the newer framework can be installed: (source: Microsoft): You may have one or more applications that are currently targeting a .NET Framework version that will no longer be supported. You can run those applications on a later .NET Framework version without targeting a new version. .NET Framework 4.5.2 and higher versions have higher compatibility, provided by a newer feature called "quirking". Quirking is a pattern in which a .NET Framework version maintains the semantics of earlier versions, while including updated implementations. The .NET runtime knows which of these semantics or quirks to execute depending on the .NET Framework version that the application targets. More information on migrating an application can be found on the Migration Guide to the .NET Framework MSDN article.
See also
Displaying Windows server OS version and edition
Displaying SQL server version and edition
Other .NET Framework topics
•To learn about installing .NET Framework, see Install downloaded prerequisites.
•Enable appropriate Framework version on a GN4 server
•Deleting .NET Framework temporary files