June 8, 2021-KB5003254 Cumulative Update for .NET Framework 3.5 and 4.8 for Windows 10, version 2004, Windows Server, version 2004, Windows 10, version 20H2, Windows Server, version 20H2 and Windows 10 Version 21H1

WPF₁

- Addresses an issue when rapid typing using an IME can crash via FailFast.

- Addresses an issue where Thaana characters displayed in left-to-right order.

- Addresses a crash when WebBrowser receives a completion event for a navigation it tried to cancel.

CLR₂

- Addresses a performance issue caused by incorrect configuration in the GC.

- Addresses an issue where a background GC could pause the runtime for a long period of time if a large managed heap is filled with long lived objects with a deep chain of references.

- Addresses an issue where crashes could occur if security stackwalks were generated during ThreadAbortException handling.

NCL₃

- .Net Framework 4.8 will now allow to negotiate TLS 1.3 if underlying OS supports it.

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)

Yes

This update will automatically sync with WSUS if you configure Products and Classifications as follows:

Product: Windows 10, version 2004, Windows Server, version 2004, Windows 10, version 20H2, and Windows Server, version 20H2, and Windows Version 21H1

Classification: Updates