October 1, 2020-KB4576945 Cumulative Update Preview for .NET Framework 3.5 and 4.8 for Windows 10, version 2004 and Windows Server, version 2004

WCF¹

- Addressed an issue with WCF services sometimes failing to start when starting multiple services concurrently.

Winforms

- Addressed a regression introduced in .NET Framework 4.8, where Control.AccessibleName, Control.AccessibleRole, and Control.AccessibleDescription properties stopped working for the following controls:Label, GroupBox, ToolStrip, ToolStripItems, StatusStrip, StatusStripItems, PropertyGrid, ProgressBar, ComboBox, MenuStrip, MenuItems, DataGridView.

- Addressed a regression in accessible name for combo box items for data bound combo boxes. .NET Framework 4.8 started using type name instead of the value of the DisplayMember property as an accessible name, this improvement uses the DisplayMember again.

ASP.NET

- Disabled resuse of AppPathModifier in ASP.Net control output.

- HttpCookie objects in the ASP.Net request context will be created with configured defaults for cookie flags instead of .NET-style primitive defaults to match the behavior of `new HttpCookie(name)`.

SQL

- Addressed a failure that sometimes occured when a user connects to one Azure SQL database, performed an enclave based operation, and then connected to another database under the same server that has the same Attestation URL and performed an enclave operation on the second server.

CLR²

- Added a CLR config variable Thread_AssignCpuGroups (1 by default) that can be set to 0 to disable automatic CPU group assignment done by the CLR for new threads created by Thread.Start() and thread pool threads, such that an app may do its own thread-spreading.

- Addressed a rare data corruption that can occur when using new API’s such as Unsafe.ByteOffset<T> which are often used with the new Span types. The corruption could occur when a GC operation is performed while a thread is calling Unsafe.ByteOffset<T> from inside of a loop.

- Addressed an issue regarding timers with very long due times ticking down much sooner than expected when the AppContext switch "Switch.System.Threading.UseNetCoreTimer" is enabled.

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.