Release Date:
January 26, 2021Version:
.NET Framework 3.5 and 4.8The January 26, 2021 update for Windows 10, version 1809 and Windows Server, version 2019 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 Prerequisite and Restart requirements sections.
Quality and reliability improvements
ASP.NET |
- Addresses an issue where after installing the update released on October 20th, some ASP.Net applications fail during precompilation – likely with a message that contains the words “Error ASPCONFIG.” |
WPF1 |
- Addresses a hang when scrolling to the end of a TreeView, when layout rounding is enabled and DPI scaling is not 100%. |
CLR2 |
- Improves the reliability of automatic Native Image generation task. |
1 Windows Presentation Foundation (WPF)
2 Common Language Runtime (CLR)Known issues with this update
Symptom |
After installing this update, WPF apps may crash with a callstack similar to
This occurs when disposing an HwndSource whose RootVisual is null, a situation that arises in Visual Studio when docking or splitting windows, and could arise in other apps. |
Workaround |
To work around this problem, set two AppContext switches using one of the methods described in AppContext Class (System) under the heading “AppContext for library consumers”. The switches are named Switch.System.Windows.Interop.MouseInput.OptOutOfMoveToChromedWindowFix and Switch.System.Windows.Interop.MouseInput.DoNotOptOutOfMoveToChromedWindowFix and both should be set to “true”. The first switch avoids the crash, but re-introduces the bug fixed in the KBs. The second switch is currently ignored, but will be recognized in a future .NET update that contains a fix for the null-reference crash; it restores the original bug fix. For example, using the app.config file method to apply the workaround at application scope:
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Additional information about this update
The following articles contain additional information about this update as it relates to individual product versions.
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4598461 Description of the Cumulative Update for .NET Framework 3.5, 4.7.2 and 4.8 for Windows 10, version 1809 and Windows Server, version 2019 (KB4598461)
How to get this update
Install this update
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. Note: This update is available on WSUS via 4598461. |
File information
For a list of the files that are provided in this update, download the file information for cumulative update.
Prerequisites
To apply this update, you must have .NET Framework 3.5 or 4.8 installed.
Restart requirement
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
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Help for installing updates: Windows Update FAQ
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Protect yourself online and at home: Windows Security support
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Local support according to your country: International Support