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This article describes hotfix rollup 3120239 that's available for the Microsoft .NET Framework 4.6 and Microsoft .NET Framework 4.6.1. For more information about the issues that the hotfix rollup fixes, see the "Issues that this hotfix rollup fixes" section.


The hotfix that corresponds to KB3120239 has been superseded with the latest updates of .NET Framework, which contain all fixes that were previously included in KB3120239. It is recommended to install the latest updates of .NET Framework.

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to obtain Microsoft support files from online services Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

More Information


To apply this hotfix, you must have the .NET Framework 4.6 or the .NET Framework 4.6.1 installed.

Restart requirement

You must restart the computer after you apply this hotfix if any affected files are being used. We recommend that you close all .NET Framework-based applications before you apply this hotfix.


Hotfix replacement information

This hotfix package doesn't replace a previously released hotfix package.

Issues that this hotfix rollup fixes

Issue 1

When you run a Windows Presentation Foundation (WPF) touch application under the system context in Windows 7 or Windows Vista, touch functionality is lost and the system crashes after a few minutes. This issue occurs because inking is not supported in the system context in Windows 7 and Windows Vista. This hotfix disables touch support when an application runs under the system context. Touch-to-mouse promotion still works. 

Issue 2

Users of WPF applications in the .NET Framework 4.6.1 may experience missing glyph symbols, such as empty square boxes, in place of normal characters for characters in the following Unicode ranges:

0000-052F, 0590-06FF, 0750-077F, 08A0-08FF, 1D00-1FFF, 2C60-2C7F, A720-A7FF, FB00-FB0F, FB1D-FBFF, FC00-FDCF, FDF0-FDFF, FE20-FE2F, FE70-FEFE

This issue occurs because of a regression that involves font fallback settings in Windows 10. This issue is more likely to occur in applications that use custom fonts that contain only a very specific set of glyphs.

­­This update fixes the WPF font fallback mappings for the .NET Framework 4.6.1 on Windows 10 and should resolve these visual issues.

Issue 3

After you install the .NET Framework 4.6 or Microsoft Visual Studio 2015, some situations that involve lots of data or many small objects may generate a FatalExecutionEngineError error because of a bug in the GC. This update fixes the condition that causes this error.

For more information about this issue, see Function returned by Microsoft.FSharp.Reflection.FSharpValue.PreComputeUnionConstructor throwing FatalExecutionEngineError when invoked.

This issue is also fixed in the .NET Framework 4.6.1.

Issue 4

An incorrect optimization that is applied by the JIT compiler can cause unpredictable behavior. The code pattern that is affected by this issue involves "if" conditions in catch blocks.

This hotfix corrects the error that causes incorrect execution of conditional statements in finally and catch handlers.

If the application still behaves unpredictably after you apply this hotfix, see additional detailed troubleshooting guidance.

Issue 5

Incorrect code optimization by the JIT can cause unpredictable application behavior after you install Visual Studio 2015 or the .NET Framework 4.6. This optimization error occurs only when the Optimization feature is turned on in Release Build in Visual Studio 2015 or in previous versions of Visual Studio after you install the .NET Framework 4.6.

If the application still behaves unpredictably after you apply this hotfix, see additional detailed troubleshooting guidance.

Additional steps:

If the troubleshooting guidance steps in the linked article help you to determine that RyuJIT may be involved in your issue, please log the issue at Microsoft Connect. Include as many details as possible together with the code to reproduce the issue.

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