This article describes hotfix rollup 3146714, which is available for the Microsoft .NET Framework 4.6 and 4.6.1. For more information about the issues that the hotfix rollup fixes, see the "Issues that this hotfix rollup fixes" section.


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Note To verify the hotfix update version, check the value of the Release keyword to determine the installed version. To be forward-compatible, you can check for a value that's greater than or equal to the value that's listed in the following table.

Hotfix rollup version

Value of the release DWORD

Hotfix rollup 3146711 for the .NET Framework 4.6 and later versions


For more information about how to determine the .NET Framework versions, see How to: Determine which .NET Framework versions are installed.

More Information


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

Restart requirement

You have to 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

CLR JIT issue   

C# structures are passed by reference, not by value, when the code is run on a computer that has the .NET Framework 4.6 installed and that's using the RyuJIT compiler. One symptom of this bug is that the code represents the data in a collection in the incorrect order (time-series). This change in behavior from earlier versions of the .NET Framework causes various symptoms when clients retrieve time-series data from our data historian.​

This issue occurs because of a missing lvAddrExposed flag for tmp variables that serve as pass-by-ref arguments, which, in turn corrupts the copy prop phase.

CLR issue

An issue in the CLR type loader may cause a deadlock while generic types are being restored from native images. This causes the ngen createpdb command​ to fail. This issue is resolved by this hotfix.

Windows Forms issue

The Windows Forms PrintPreviewDialog UI is initialized very slowly when the following conditions are true:

  • A network printer is used.

  • User preferences for this printer, such as duplex settings, are modified.

We added a performance optimization to this scenario. If page settings were not modified for a specific page, printer settings for this page are not reapplied (by accessing to the printer spooler). If the application modifies printer settings by using the QueryPageSettings event handler, print preview generation performance for the affected pages does not improve even if the opt-in flag is set.

In order to opt in to this optimization, the following key should be added to the app.config file depending on the version of the .NET Framework:

.NET Framework 4.5.2:

<?xml version="1.0" encoding="utf-8"?>
< appSettings >
< add key="OptimizePrintPreview" value="true" />
< /appSettings >
</configuration> .NET Framework 4.6 or a later version:

<?xml version="1.0" encoding="utf-8"?>
< runtime>
< AppContextSwitchOverrides value = "Switch.System.Drawing.Printing.OptimizePrintPreview=true" />
< /runtime>
</configuration> If an application can run on either version of the .NET Framework, use both switches in the same file.

To opt out, remove the switch, or set the values to false. ​

ClickOnce issue

ClickOnce has been updated to support TLS 1.1 and 1.2. ClickOnce automatically detects which TLS protocol is required at runtime. There are no extra steps required in ClickOnce to enable this functionality.

Note ClickOnce continues to support TLS 1.0 for the foreseeable future, even though it is no longer considered PCI-compliant.​

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