Release Date:November 19, 2021

Version: .NET Framework 3.5 and 4.8

The November 19, 2021 update for Microsoft server operating system version 21H2 includes cumulative reliability improvements in .NET Framework 3.5 and 4.8. 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.

Summary

Security improvements

There are no new security improvements in this release. This update is cumulative and contains all previously released security improvements.

Quality and reliability improvements

WPF1

- Addresses an issue where WPF does not respond to touch if the WPF window was activated by a touch manipulation (e.g. swiping a listbox).

- Adds a mitigation for an issue involving tearing, flickering, or incorrect composition of visual content under high GPU-load conditions.

- Addresses an issue where the extra information associated with a WM_KEYDOWN message is discarded before the handlers for the PreviewKeyDown or KeyDown events can retrieve it via GetMessageExtraInfo.

- Addresses an issue where AutomationElement.FindFirst or FindAll do not search the subtree of an hwnd whose UIA_WindowVisibilityOverridden property is set to 1.

- Addresses an issue where a binding on TextBox.Text with UpdateSourceTrigger=PropertyChanged produces incorrect results when the Microsoft Quick IME is used.

SQL Connectivity

- Under certain error cases caused due to NullReferenceException thrown while populating SqlParameter values using customer provided delegates, the SqlClient driver may not cleanup the state of connection state. The connection in bad state, can make its way into the connection pool and may be picked up for reuse causing unexpected failures on the connection. If such a condition is recognized, an AppContext Switch “Switch.System.Data.SqlClient.CleanupParserOnAllFailures”, may be enabled to clean up connections on any kind of failures even while running into errors with delegates.

WCF2

- Addresses a failure to correctly timeout a failed request when making an asynchronous WCF call over HTTP. If the service has sent a partial response message and fails to send the remainder of the response, the client may not fail the call after the configured timeout.

1 Windows Presentation Foundation (WPF)2 Windows Communication Foundation (WCF)

How to get this update

Install this update

Release Channel

Available

Next Step

Windows Update and Microsoft Update

Yes

To download and install this update, go to Settings > Update & Security > Windows Update, and then select Check for updates.

Windows Update for Business

No

None. These changes will be included in the next security update to this channel. For more information about Windows Update for Business go to the Windows Update for Business website.

Microsoft Update Catalog

Yes

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Windows Server Update Services (WSUS)

No

You can import this update into WSUS manually. See the Microsoft Update Catalog for instructions.

File information

For a list of the files that are provided in this update, download the file information for cumulative update.

Prerequisites

To apply this update, you must have .NET Framework 3.5 or 4.8 installed.

Restart requirement

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.

How to obtain help and support for this update

Known issues in this update

Microsoft is not currently aware of any issues in this update.

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