Yesterday, we released the February 2021 Cumulative Update Preview for .NET Framework.

Quality and Reliability

This release contains the following quality and reliability improvements.

CLR¹

• Addresses an issue where the entire process would be torn down when a NullReferenceException propagated out of an exception filter.
• Addresses an issue with slowdowns that could occur when making large numbers of devirtualized calls into MarshalByRefObject-derived code.

WPF²

• Addresses an issue with lag responding to typing in TextBox, when spell-checking is enabled that was introduced in an update earlier this year.
• Addresses an issue with a leak of touch-related resources, including OS handles, when closing a window. The leak only occurs when a touch device is active, and only for windows whose HwndSource is created directly by the app.
• Addresses a crash when docking a window within Visual Studio, or, more generally, disposing an HwndSource whose RootVisual is null.

Winforms

• Addresses an issue in ComboBox drop down item bounding rectangle as exposed to the accessibility tools, where we did not take into account that some items might be scrolled out of view, we had always started counting items from the first visible one, and thus item rectangle location was incorrect.
• Implemented ScrollItemPattern (IScrollItemProvider (uiautomationcore.h) – Win32 apps | Microsoft Docs) for ComboBox drop down items.

¹ Common Language Runtime (CLR) ² Windows Presentation Foundation (WPF)

Known issues in this update

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

Getting the Update

The Cumulative Update Preview is available via Windows Update and Microsoft Update Catalog.

Microsoft Update Catalog

You can get the update via the Microsoft Update Catalog.  Customers that rely on Windows Update will automatically receive the .NET Framework version-specific updates. Advanced system administrators can also take use of the below direct Microsoft Update Catalog download links to .NET Framework-specific updates. Before applying these updates, please ensure that you carefully review the .NET Framework version applicability, to ensure that you only install updates on systems where they apply.

The following table is for Windows 10 and Windows Server 2016+ versions.

Previous Monthly Rollups

The last few .NET Framework Monthly updates are listed below for your convenience:

• .NET Framework February Security and Quality Rollup Update
• .NET Framework January Security and Quality Rollup Update