.NET Framework September 2019 Preview of Quality Rollup

Brett Lopez

We have released the September 2019 Preview of Quality Rollup and Cumulative Updates for .NET Framework for Windows 10

Quality and Reliability

This release contains the following quality and reliability improvements.

BCL¹

• Addresses an issue that affects thread contention that occurs in BinaryFormatter.GetTypeInformation by using ConcurrentDictionary to handle multi-thread access.

CLR²

• Addresses an issue that might cause handle leaks to occur in scenarios that repeatedly load and unload Mscoree.dll.
• Addresses rare cases that incorrectly cause process termination instead of delivering the expected NullReferenceException result.

WPF³

• Addresses an issue that affects a WPF ComboBox (or any Selector) within a DataGrid cell that can try to change its selection properties (SelectedIndex, SelectedItem, SelectedValue) when the cell’s data item is re-virtualized or removed from the underlying collection. This can occur if the Selector’s ItemSource property is data bound through the cell’s DataContext setting. Depending on the virtualization mode and the bindings that are declared for the selection properties, the symptoms can include unexpected changes (to null) of the data item’s properties, and unexpected displays (as null) of other data items that re-use the UI that was previously attached to the re-virtualized item.
• Addresses an issue in which a WPF TextBox or RichTextBox element that has spell checking enabled crashes and returns an “ExecutionEngineException” error in some situations, including inserting text near a hyperlink.
• Addresses an issue that affects Per-Monitor Aware WPF applications that host System-Aware or Unaware child windows and that run on .NET Framework 4.8. This .NET version occasionally crashes and returns a “System.Collections.Generic.KeyNotFoundException” exception.

¹ Base Class Library (BCL)
² Common Language Runtime (CLR)
³ Windows Presentation Foundation (WPF)

Getting the Update

The Preview of Quality Rollup is available via Windows Update, Windows Server Update Services, and Microsoft Update Catalog.

Microsoft Update Catalog

You can get the update via the Microsoft Update Catalog. For Windows 10, NET Framework 4.8 updates are available via Windows Update, Windows Server Update Services, Microsoft Update Catalog.  Updates for other versions of .NET Framework are part of the Windows 10 Monthly Cumulative Update.

Note: Customers that rely on Windows Update and Windows Server Update Services 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.

The following table is for earlier Windows and Windows Server versions.

Previous Monthly Rollups

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

• September 2019 Security and Quality Rollup
• August Cumulative Update for Windows 10 version 1903
• August 2019 Preview of Quality Rollup

Brett Lopez .NET Framework

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