This August 2017 Update for Windows 8.1 and Windows Server 2012 R2 fixes an issue in the .NET Framework 4.6, 4.6.1, 4.6.2, and 4.7. We recommend that you apply this update as part of your regular maintenance routines. Before you install this update, see the "Prerequisites" and "Restart requirement" sections.
Common Language Runtime (CLR)
Applications that run on the .NET Framework do not respect the settings that are specified in the registry for AppContext switches. Regardless of the registry option setting for an AppContext flag, the application behaves as if the value specified is set to "false."
How to get this update
For Windows 8.1 and Windows Server 2012 R2
This update is available by manual download only.
To get the stand-alone package for this update, go to the Microsoft Update Catalog website.
To apply this update, you must have the .NET Framework 4.6, 4.6.1, 4.6.2, or 4.7 installed.
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.