August 10, 2021 - KB5004331 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10, version 2004, Windows Server, version 2004, Windows 10, version 20H2, and Windows Server, version 20H2, and Windows Version 21H1

The August 10, 2021 update for Windows 10, version 2004, Windows Server, version 2004, Windows 10, version 20H2, and Windows Server, version 20H2, and Windows Version 21H1 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

CLR1

- In scenarios with both high numbers of assemblies and high numbers of GC heaps, Server GC can encounter serious lock contention during generation 2 GCs. A config switch has been introduced as a workaround. It can either be enabled from a .config file: <configuration> <runtime> <GCStaticsNoLock enabled="true"/> </runtime> </configuration> Or by setting environment variable COMPLUS_GCStaticsNoLockto a non-zero value. If the config switch is not enabled, behavior is unchanged compared to previous versions.

Winforms

- Addresses an issue where some Windows Forms applications that use ToolStrip controls with ToolStripControlHost, and run under UIA Accessibility Tools, could make Accessibility Tools unresponsive. - Addresses a regression in the ComboBox item accessible object where Accessibility Tools was not able to distinguish between identical items in the ComboBox and was becoming unresponsive.

₁ Common Language Runtime (CLR)

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.
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

• Help for installing updates: Windows Update FAQ
• Protect yourself online and at home: Windows Security support
• Local support according to your country: International Support

Known issues in this update

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

Source: https://support.microsoft.com/en-us/...4-c04f55cd1d08

See also: https://devblogs.microsoft.com/dotne...pdate-preview/


Direct download links for KB5004331 MSU file from Microsoft Update Catalog:

Download KB5004331 MSU for Windows 10 v2004, v20H2, and v21H1 32-bit (x86) - 41.8 MB

Download KB5004331 MSU for Windows 10 v2004, v20H2, and v21H1 64-bit (x64) - 65.4 MB

Download KB5004331 MSU for Windows 10 v2004, v20H2, and v21H1 ARM64 - 41.8 MB

Posted By: Brink
29 Jul 2021