Release Date:July 21, 2020
Version: .NET Framework 3.5 and 4.7.2
The July 21, 2020 update for Windows 10 Version 1809 and Windows Server 2019 includes cumulative reliability improvements in .NET 3.5 and 4.7.2. 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.
Quality and reliability improvements
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CLR1 |
- Addresses rare crashes that could occur during thread abort delivery. |
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ASP.NET |
- Use FIPS-compliant hashes in ASP.Net telemetry data. - Addresses an issue where "Unspecified" was not an allowed value in config for the 'cookieSameSite' attribute of the forms authentication and session state configuration sections. - Addresses an issue where first requests to a cold site sometimes return a server configuration error from System.Web.DirectoryMonitor.AddFileMonitor(). |
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WPF2 |
- Addresses an issue where TextBlock reflows (makes different line-breaking decisions) during render and hit-test, vs. during measure. The symptoms include missing text, and FailFast crashes during programmatic text processing. - Addresses a render thread failure caused by HostVisual disconnecting its target on the wrong thread. - Addresses a hang while scrolling a TreeView whose tree is non-uniform, in the sense thata given node's children govern subtrees whose sizes are quite different. - DataGrid's Copy command throws an exception if the system clipboard is locked by another process. This crashes, as there is usually no app code on the stack to catch the exception. The behavior of TextBox (and other apps like Notepad, Word, browsers) in this situation is to fail silently - nothing is copied to the clipboard, but no exception. A WPF app can now opt-in to this behavior by setting <appSettings> <add key="ShouldThrowOnDataGridCopyOrCutFailure" value="false"/> </appSettings>in its app.config file. - Addresses the way non-animated text with TextRenderingMode="ClearType" and TextFormattingMode="Ideal" is drawn. It now uses a symmetric anti-aliasing algorithm, which produces better visual results for text with fine strokes (common in Far East languages, Arabic, Hebrew, and fonts designed specifically for symmetric anti-aliasing). - Addresses a crash that can occur when closing a tooltip that is re-entrantly closed by user code. - Addresses a memory leak in System.Speech.SpeechSynthesizer. - Addresses issues in constructing the internal model for a FixedPage document. Some text was appearing in the wrong order for the purposes of editing operations such as selection and copy/paste. |
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Net Libraries |
- Addresses a memory leak in HttpListener. |
1 Common Language Runtime (CLR)2 Windows Presentation Foundation (WPF)
Known issues in this update
Windows Presentation Framework (WPF) applications that use two or more HostVisual elements belonging to a common thread, where both HostVisual elements are asked to disconnect from their visual target at roughly the same time, mail fail with the following error:
Exception type: System.COMException Message: UCEERR_RENDERTHREADFAILURE (HRESULT 0x88980406) Callstack: top frame is System.Windows.Media.Composition.DUCE+Channel.SyncFlush()
Workarounds
You can disable the problematic fix by setting the AppContext switch “Switch.System.Windows.Media.HostVisual.DisconnectsOnWrongThread” to true, using one of the methods described here. This exposes your app to the original bug, so you should remove the switch once a fix is published through an upcoming update.
Workaround 1
• Add the following entry to the app.config file to disable the problematic fix in a single application.
<runtime> <AppContextSwitchOverrides value="Switch.System.Windows.Media.HostVisual.DisconnectsOnWrongThread=true"/> </runtime>
Note that if your application configuration already has an entry for <AppContextSwitchOverrides>, you need to add the new setting within that entry, separated from other switches by a semicolon:
<AppContextSwitchOverrides value="Switch.SomeOtherSwitch=true; Switch.System.Windows.Media.HostVisual.DisconnectsOnWrongThread=true"/>
Workaround 2
• Apply the following registry subkey to disable the problematic fix for all WPF applications on the machine. Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft can't guarantee that these problems can be solved. Modify the registry at your own risk.
Location: HKEY_LOCAL_MACHINE\Software\Microsoft\.NETFramework\AppContext\ Name: Switch.System.Media.HostVisual.DisconnectsOnWrongThread Type: String Value: true
Note that on 64-bit operating systems, you also need to apply a registry subkey with the same name, type, and value at the location: HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\.NETFramework\AppContext\
Resolution
We are working on a resolution and will provide an update in an upcoming release.
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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4567327 Description of the Cumulative Update Preview for .NET Framework 3.5, 4.7.2 and 4.8 for Windows 10 Version 1809 and Windows Server 2019 (KB4567327)
How to obtain and install the update
Install this update
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Release Channel |
Available |
Next Step |
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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. |
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Microsoft Update Catalog |
Yes |
To get the standalone package for this update, go to the Microsoft Update Catalog website. |
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Windows Server Update Services (WSUS) |
No |
You can import this update into WSUS manually. See the Microsoft Update Catalog for instructions. |
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 4.7.2 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
