January 12, 2021-KB4586878 Cumulative Update Preview for .NET Framework 3.5 and 4.8 for Windows 10, version 1903, Windows Server, version 1903, Windows 10, version 1909 and Windows Server, version 1909
January 12, 2021
.NET Framework 3.5 and 4.8
This update for Windows 10, version 1903, Windows Server, version 1903, Windows 10, version 1909 and Windows Server, version 1909 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.
This update is included in the Cumulative Update that is dated January 12, 2021. This update was previously released in the Cumulative Update that was dated November 19, 2020.
Quality and reliability improvements
- Addressed an issue with a FailFast crash arising in apps with two threads that both load application resources.
- Improved the clean-up process for X509Certificate2 certificates. For more information see KB5001206.
1 Windows Presentation Foundation (WPF)
How to obtain and install the update
Install this update
This update will be downloaded and installed automatically from Windows Update.
To get the standalone package for this update, go to the Microsoft Update Catalog website.
For a list of the files that are provided in this update, download the file information for cumulative update.
To apply this update, you must have .NET Framework 3.5 or 4.8 installed.
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