A new update for .NET Framework is now available for the AppContext class. The behavior of the AppContext class was recently regressed. The update returns the class to the correct behavior. This update affects the .NET Framework 4.6 and later. The update is not required on Windows 10.

The AppContext class was introduced in the .NET Framework 4.6. It’s primary use is to enable developers to opt into new behavior in the .NET Framework that is not enabled by default. The regression prevents developers from opting into new behavior.

You are only encouraged to install this update if you have used the AppContext class directly and are experiencing problems. Otherwise, you will get this update in one of the regular broader releases over the next one to two months.

Getting the Update

This update is available via the Microsoft Update Catalog.

Downloading KBs from Microsoft Update Catalog

You can download patches from the table below. See .NET Framework Monthly Rollups Explained for an explanation on how to use this table to download patches from Microsoft Update Catalog.

Windows 8.1
Windows RT 8.1
Windows Server 2012 R2

• Catalog
• 4038922

.NET Framework 4.6, 4.6.1, 4.6.2, 4.7

• 4038922

Windows Server 2012

• Catalog
• 4038921

.NET Framework 4.6, 4.6.1, 4.6.2, 4.7

• 4038921

Windows 7
Windows Server 2008 R2 SP1

• Catalog
• 4038923

.NET Framework 4.6, 4.6.1, 4.6.2, 4.7

• 4038923

Windows Server 2008 SP2

• Catalog
• 4038923

.NET Framework 4.6

• 4038923

Source: https://blogs.msdn.microsoft.com/dot...or-appcontext/

Posted By: Brink
18 Aug 2017